The research firm should use the following procedure to analyze the data for the mean difference in salary within married couples:
a) One-sample t procedure, matched pair
It is because, The "matched pair" aspect indicates that each husband's salary is paired with his respective wife's salary. This pairing is essential because the focus is on comparing the salaries within each couple.
The one-sample t procedure is appropriate in this scenario because it compares the mean salary difference within each couple to determine if there is a significant difference between what husbands and wives earn.
This procedure is suitable when the same sample is measured twice (in this case, the salaries of husbands and wives in each couple) and the goal is to compare the means of the differences within the pairs.
By using the one-sample t procedure with matched pairs, the research firm can effectively analyze the data and draw conclusions regarding the mean salary difference within married couples.
The complete question: A research firm wants to determine whether there is a difference in married couples between what the husband earns and what the wife earns. The firm takesa random sample of married couples and measures the annual salary of each husband and wife. What procedure should the firm use to analyze the data for the mean difference in salary within married couples?
a)One-sample t procedure, matched pair
b)Two-sample t procedure
c)One-sample z procedure, matched pair
d)Two-sample z procedure
e)Not enough information to
Clare is using little wooden cubes with edge length 1/2 inch to build a larger cube that has edge length 4 inches. How many little cubes does she need? explain your reasoning
To form a larger 4-inch cube, Clare will need 512 wooden cubes with an edge length of 1/2 inch. We find this by dividing the volume of the large cube (64 cubic inches) by the volume of the small one (1/8 cubic inch).
Explanation:Clare is building a larger cube with an edge length of 4 inches, consisting of smaller wooden cubes each with an edge length of 1/2 inch. To solve this problem, we need to find out how many smaller cubes make up the volume of the larger cube. The volume of a cube is found by multiplying the length of an edge by itself three times, or cube the edge length.
So first, we calculate the volume of the large cube which is 4in * 4in * 4in = 64 cubic inches.
Next, we calculate the volume of a small cube which is (1/2in) * (1/2in) * (1/2in) = 1/8 cubic inch.
Finally, we divide the volume of the large cube by the volume of the small cube to find out how many small cubes are needed. Thus, 64 cubic inches / 1/8 cubic inch = 512. So, Clare will need 512 small wooden cubes to construct her larger cube.
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To find the number of little cubes needed, divide the volume of the larger cube by the volume of each little cube.
Explanation:To find the number of little cubes Clare needs to build a larger cube with an edge length of 4 inches, we need to
determine the volume of the larger cube and divide it by the volume of each little cube.
The volume of the larger cube is calculated by multiplying the length of one side by itself three times (4 x 4 x 4 = 64 cubic inches).
The volume of each little cube is calculated by multiplying the length of one side by itself three times (1/2 x 1/2 x 1/2 = 1/8 cubic inches).
To find the number of little cubes needed, we divide the volume of the larger cube by the volume of each little cube (64 / (1/8) = 512 little cubes).
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If two events are mutually exclusive, what is the probability that one or the other occurs?
In probability, if two events are mutually exclusive (cannot occur at the same time), the probability of either event occurring is calculated by adding the probabilities of each event separately.
Explanation:The concept being referred to in your question is related to probability within the study of mathematics. When two events are mutually exclusive, it means they cannot occur at the same time. For example, when rolling a die, the events of throwing a '6' and a '3' are mutually exclusive; you cannot throw both on a single toss.
In reference to your question, the probability that one event or the other occurs, given that they are mutually exclusive, is calculated by adding the probabilities of each individual event. So if the probability of Event A is P(A) and the probability of Event B is P(B), then the probability that either A or B will occur (P(A U B)) equals P(A) + P(B).
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On the Richter Scale, the magnitude R of an earthquake of intensityI is
R = log10 I/Io
where lo is a reference intensity. At 7:23am on March 19, 2003, an earthquake measuring 3.0 on the Richter scale occurred near the town of Nephi. An earthquake of that magnitude is often felt, but rarely causes damage. By comparison, the earthquake that struck San Francisco in 1906 measured 8.25 on the Richter scale. It was ___________times as intensive as the Nephi earthquake.
Answer:
177,827.941
Step-by-step explanation:
The magnitude of an earthquake is given by:
[tex]R=log(\frac{l}{l_0})[/tex]
The intensity of the Nephi earthquake is:
[tex]3.0=log(\frac{l_N}{l_0})\\10^3 =\frac{l}{l_0} \\l_N=1,000*l_0[/tex]
The intensity of the San Francisco earthquake is
[tex]8.25=log(\frac{l_S}{l_0})\\10^{8.25} =\frac{l_S}{l_0} \\l_S=177,827,941*l_0[/tex]
The intensity ratio is:
[tex]r= \frac{l_S}{l_N}=\frac{177,827,941*l_0}{1,000*l_0}\\r= 177,827.941[/tex]
The San Francisco earthquake was 177,827.941 times as intensive as the Nephi earthquake.
When comparing the intensity of the San Francisco earthquake (magnitude 8.25) and the Nephi earthquake (magnitude 3.0) on the Richter Scale, we find that the San Francisco earthquake was approximately 177,827.94 times more intensive than the Nephi earthquake.
Explanation:To compare the intensity of two earthquakes using the Richter Scale, we need to apply the formula:
R = log10 I/Io, where R is the Richter magnitude, I is the intensity of the earthquake, and Io is a reference intensity.
Now, we know that the Richter scale is a base-10 logarithmic scale. This means that each whole number increase on the scale represents a tenfold increase in measured amplitude and roughly 31.6 times more energy release.
The earthquakes in question have magnitudes of 3.0 and 8.25. So, the intensity of the San Francisco earthquake compared to the Nephi earthquake is 10^(8.25-3) = 10^5.25.
Therefore, the San Francisco earthquake was approximately 177,827.94 times more intensive as the Nephi earthquake.
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simplify (3/4 + 4/5i)-(1/2 - 3/10i)
For this case we must simplify the following expression:
[tex](\frac {3} {4} + \frac {4} {5} i) - (\frac {1} {2} - \frac {3} {10} i) =[/tex]
By law of multiplication signs we have to:
[tex]- * + = -\\- * - = +\\\frac {3} {4} + \frac {4} {5} i- \frac {1} {2} + \frac {3} {10} i =[/tex]
We add similar terms:
[tex]\frac {3} {4} - \frac {1} {2} + \frac {4} {5} i + \frac {3} {10} i =\\\frac {3 * 2-4 * 1} {4 * 2} + \frac {4 * 10 + 5 * 3} {10 * 5} i =\\\frac {2} {8} + \frac {55} {50} i =[/tex]
We simplify:
[tex]\frac{1}{4}+\frac{11}{10}i[/tex]
Answer:
[tex]\frac{1}{4}+\frac{11}{10}i[/tex]
A researcher wishes to determine the average number of vehicles are registered to a typical Houston residence. In order to do this, he sends a survey to 250 randomly selected residences asking for them to indicate the number of registered and return the survey. Identify the population.
Answer: Houston residences
Step-by-step explanation:
A population is the group of members comes under the same criteria by the researcher's point of view.Here , The objective of the researcher is to determine the average number of vehicles are registered to a typical Houston residence.
Clearly , the population is this situation is "Houston residences" having vehicles.
Note : 250 randomly selected residences are defining the sample of the entire population of Houston residences which is a subset of population.
Hence, the correct answer is Houston residences.
The mean consumption of bottled water by a person in the United States is 28.5 gallons per year. You believe that a person consume more than 28.5 gallons in bottled water per year. A random sample of 100 people in the United States has a mean bottled water consumption of 27.8 gallons per year with a standard deviation of 4.1 gallons. At α = 0.10 significance level can you reject the claim?
Answer:
[tex]t=\frac{27.8-28.5}{\frac{4.1}{\sqrt{100}}}=-1.707[/tex]
[tex]p_v =P(t_{99}<-1.707)=0.0455[/tex]
If we compare the p value with a significance level for example [tex]\alpha=0.1[/tex] we see that [tex]p_v<\alpha[/tex] so we can conclude that we reject the null hypothesis, so there is not enough evidence to conclude that the mean for the consumption is less than 28.5 gallons at 0.1 of significance, so we can reject the claim that person consume more than 28.5 gallons.
Step-by-step explanation:
Data given and notation
[tex]\bar X=27.8[/tex] represent the mean for the account balances of a credit company
[tex]s=4.1[/tex] represent the population standard deviation for the sample
[tex]n=1000[/tex] sample size
[tex]\mu_o =28.5[/tex] represent the value that we want to test
[tex]\alpha=0.1[/tex] represent the significance level for the hypothesis test.
t would represent the statistic (variable of interest)
[tex]p_v[/tex] represent the p value for the test (variable of interest)
State the null and alternative hypotheses.
We need to conduct a hypothesis in order to determine if the mean for the person consume is more than 28.5 gallons, the system of hypothesis would be:
Null hypothesis:[tex]\mu \geq 28.5[/tex]
Alternative hypothesis:[tex]\mu < 28.5[/tex]
We don't know the population deviation, so for this case we can use the t test to compare the actual mean to the reference value, and the statistic is given by:
[tex]t=\frac{\bar X-\mu_o}{\frac{s}{\sqrt{n}}}[/tex] (1)
t-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".
Calculate the statistic
We can replace in formula (1) the info given like this:
[tex]t=\frac{27.8-28.5}{\frac{4.1}{\sqrt{100}}}=-1.707[/tex]
Calculate the P-value
First we need to calculate the degrees of freedom given by:
[tex]df=n-1=100-1=99[/tex]
Since is a one-side lower test the p value would be:
[tex]p_v =P(t_{99}<-1.707)=0.0455[/tex]
In Excel we can use the following formula to find the p value "=T.DIST(-1.707,99)"
Conclusion
If we compare the p value with a significance level for example [tex]\alpha=0.1[/tex] we see that [tex]p_v<\alpha[/tex] so we can conclude that we reject the null hypothesis, so there is not enough evidence to conclude that the mean for the consumption is less than 28.5 gallons at 0.1 of significance, so we can reject the claim that person consume more than 28.5 gallons.
Use trigonometric identities and algebraic methods, as necessary, to solve the following trigonometric equation. Please identify all possible solutions by including all answers in [0,2Ï€) and indicating the remaining answers by using n to represent any integer. Round your answer to four decimal places, if necessary. If there is no solution, indicate "No Solution." cos2(5x)=sin2(5x)
Answer:
[tex]\large\boxed{x=\pm\dfrac{3\pi}{20}+\dfrac{2n\pi}{5}\ \vee\ x=\pm\dfrac{\pi}{20}+\dfrac{2n\pi}{5}}[/tex]
Step-by-step explanation:
[tex][tex]\cos^2(5x)=\sin^2(5x)\qquad\text{substitute}\ t=5x\\\\\cos^2t=\sin^2t\qquad\text{use}\ \sin^2\theta+\cos^2\theta=1\to\sin^2\theta=1-\cos^2\theta\\\\\cos^2t=1-\cos^2t\qquad\text{add}\ \cos^2t\ \text{to both sides}\\\\2\cos^2t=1\qquad\text{divide both sides by 2}\\\\\cos^2t=\dfrac{1}{2}\Rightarrow \cos t=\pm\sqrt{\dfrac{1}{2}}\\\\\cos t=\pm\dfrac{\sqrt2}{2}\\\\\cos t=-\dfrac{\sqrt2}{2}\Rightarrow t=\pm\dfrac{3\pi}{4}+2n\pi\\\\\cos t=\dfrac{\sqrt2}{2}\Rightarrow t=\pm\dfrac{\pi}{4}+2n\pi[/tex]
[tex]t=5x\\\\5x=\pm\dfrac{3\pi}{4}+2n\pi\ \vee\ 5x=\pm\dfrac{\pi}{4}+2n\pi\qquad\text{divide both sides by 5}\\\\x=\pm\dfrac{3\pi}{20}+\dfrac{2n\pi}{5}\ \vee\ x=\pm\dfrac{\pi}{20}+\dfrac{2n\pi}{5}[/tex]
The trigonometric equation 2cos^2(x) + 2 = 4 has solutions x = 0 and x = π in the interval [0, 2π). To include all possible solutions, we express them as x = 2nπ and x = π + 2nπ with n as any integer.
To solve the trigonometric equation 2cos^2(x) + 2 = 4, we start by simplifying the equation:
Subtract 2 from both sides to get 2cos^2(x) = 2.Divide both sides by 2 to get cos^2(x) = 1.Take the square root of both sides, considering both positive and negative roots, to get cos(x) = ±1.Find angles x in the interval [0, 2π) where the cosine is ±1. For cos(x) = 1, x = 0. For cos(x) = -1, x = π.This equation has two solutions in the interval [0, 2π): x = 0 and x = π (which are 0 and 3.1416 when rounded to four decimal places). To express the infinite set of solutions that occur at every period of cos(x), we add 2nπ to each solution, where n is any integer, giving the final solutions as x = 2nπ and x = π + 2nπ.
the complete Question is given below:
Use trigonometric identities and algebraic methods, as necessary, to solve the following trigonometric equation. Please identify all possible solutions by including all answers in [0, 2π)
and indicating the remaining answers by using n to represent any integer. Round your answer to four decimal places, if necessary. If there is no solution, indicate "No Solution."
2cos^2 (x) + 2 = 4
Enter your answer in radians, as an exact answer when possible. Multiple answers should be separated by commas.
......Help Please......
Answer:
Step-by-step explanation:
the sign here means division
7 divided by the number in the box equals to 8
simply meaning 7 multiplied by 8 will give the number
7 x 8 = 56
Compute Δy and dy for the given values of x and dx = Δx. (Round your answers to three decimal places.) y = x , x = 1, Δx = 1 Δy = dy =
Answer:
Δy = 1
dy = 1
Step-by-step explanation:
Data provided in the question:
dx = Δx
y = x
x = 1,
Δx = 1
Now,
we know,
Δy = f( x + Δx ) - f(x)
also, we have
y = f(x) = x
thus,
f( x + Δx ) = x + Δx
Therefore,
Δy = ( x + Δx ) - x
on substituting the respective values, we get
Δy = ( 1 + 1 ) - 1
or
Δy = 1
and,
dy = f'(x) = [tex]\frac{d(x)}{dx}[/tex]
or
dy = 1
The brand manager for a brand of toothpaste must plan a campaign designed to increase brand recognition. He wants to first determine the percentage of adults who have heard of the brand. How many adults must he survey in order to be 80% confident that his estimate is within six percentage points of the true populationpercentage?
Complete parts (a) through (c) below.
1) Assume that nothing is known about the percentage of adults who have heard of the brand.
a.n=_________(Round up to the nearest integer.)
2) Assume that a recent survey suggests that about 85% of adults have heard of the brand.
b.n=_________(Round up to the nearest integer.)
3) Given that the required sample size is relatively small, could he simply survey the adults at the nearest college?
Answer:
1) n=114
2) n=59
3) On this case no, because if we survey just the adults of the nearest college that would be a convenience sample. And when we use "convenience sample" we have some problems associated to bias. This methodology it's not appropiate in order to have a good estimation of the parameter of interest. It's better use a random, cluster or stratified sampling.
Step-by-step explanation:
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The population proportion have the following distribution
[tex]p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})[/tex]
In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 80% of confidence, our significance level would be given by [tex]\alpha=1-0.80=0.2[/tex] and [tex]\alpha/2 =0.1[/tex]. And the critical value would be given by:
[tex]z_{\alpha/2}=-1.28, z_{1-\alpha/2}=1.28[/tex]
Part 1
The margin of error for the proportion interval is given by this formula:
[tex] ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}[/tex] (a)
And on this case we have that [tex]ME =\pm 0.06[/tex] or 6% points, and we are interested in order to find the value of n, if we solve n from equation (a) we got:
[tex]n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}[/tex] (b)
Since we don't have a prior estimate of [tex]\het p[/tex] we can use 0.5 as a good estimate, replacing into equation (b) the values from part a we got:
[tex]n=\frac{0.5(1-0.5)}{(\frac{0.06}{1.28})^2}=113.77[/tex]
And rounded up we have that n=114
Part 2
On this case we have a prior estimate for the population proportion and is [tex]\hat p =0.85[/tex] so replacing the values into equation (b) we got:
[tex]n=\frac{0.85(1-0.85)}{(\frac{0.06}{1.28})^2}=58.027[/tex]
And rounded up we have that n=59
Part 3
On this case no, because if we survey just the adults of the nearest college that would be a convenience sample. And when we use "convenience sample" we have some problems associated to bias. This methodology it's not appropiate in order to have a good estimation of the parameter of interest. It's better use a random, cluster or stratified sampling.
In many population growth problems, there is an upper limit beyond which the population cannot grow. Many scientists agree that the earth will not support a population of more than 16 billion. There were 2 billion people on earth in 1925 and 4 billion in 1975. If is the population years after 1925, an appropriate model is the differential equationdy/dt=ky(16-y)Note that the growth rate approaches zero as the population approaches its maximum size. When the population is zero then we have the ordinary exponential growth described by y'=16ky. As the population grows it transits from exponential growth to stability.(a) Solve this differential equation.(b) The population in 2015 will be(c) The population will be 9 billion some time in the year
Answer:
a) (y-16)/y = -7*e∧(-0.016946*t)
b) y = 6.34
c) t = 129.66 years in 2055
Step-by-step explanation:
a) dy/dt = ky*(16-y)
Solving the differential equation we have
dy / (y*(y-16)) = -k dt
∫ dy / (y*(y-16)) = ∫ -k dt
(-1/16)*Ln (y) + (1/16)*Ln (y-16) = -k*t + C
(1/16) Ln ((y-16)/y) = -k*t + C
Ln ((y-16)/y) = -16*k*t + C
(y-16)/y = C*e∧(-16*k*t)
If t = 0 and y = 2
(2-16)/2 = C*e∧(0)
C = -7 then we have
(y-16)/y = -7*e∧(-16*k*t)
In 1975 we have t = 1975 - 1925= 50 years and y = 4
(4-16)/4 = -7*e∧(-16*k*50)
k= - Ln (3/7) / 800 = 0.001059
Finally, the differential equation will be
(y-16)/y = -7*e∧(-16*0.001059*t)
(y-16)/y = -7*e∧(-0.016946*t)
b) In 2015 we have t = 2015 – 1925 = 90 years
(y-16)/y = -7*e∧(-0.016946*90)
Solving the equation we get
y = 6.34
c) If y = 9
(9-16)/9 = -7*e∧(-0.016946*t)
t = 129.66 years in 2055
The solution for (a)[tex]a) (y-16)/y = -7*e^{(-0.016946*t)}[/tex]b) y = 6.34 and (c) the value of t is 129.66 years in 2055
We have given that,
[tex]a) dy/dt = ky*(16-y)[/tex]
By using variable separable form we have,
What is the variable separable form?A variable separable differential equation is any differential equation in which variables can be separated
Therefore by solving the differential equation we have
[tex]dy / (y*(y-16)) = -k dt[/tex]
integrating both side with respect to t
[tex]\int dy / (y*(y-16)) = \int -k dt[/tex]
Solve the integration of the above
[tex](-1/16)*ln (y) + (1/16)*ln (y-16) = -k*t + C[/tex]
[tex](1/16) ln ((y-16)/y) = -k*t + C[/tex]
[tex]ln ((y-16)/y) = -16*k*t + C[/tex]
[tex](y-16)/y = C*e^{(-16*k*t)}[/tex]
If t = 0 and y = 2
[tex](2-16)/2 = C*e^{0}[/tex]
C = -7 then we have
[tex](y-16)/y = -7*e^{(-16*k*t)}[/tex]
In 1975 we have t = 1975 - 1925= 50 years and y = 4
[tex](4-16)/4 = -7*e^{(-16*k*50)[/tex]
[tex]k= - Ln (3/7) / 800 = 0.001059[/tex]
Finally, the differential equation will be
[tex](y-16)/y = -7*e^{(-16*0.001059*t)}[/tex]
[tex](y-16)/y = -7*e^{(-0.016946*t)}[/tex]
b) In 2015 we have t = 2015 – 1925 = 90 years
[tex](y-16)/y = -7*e^{(-0.016946*90)}[/tex]
Solving the equation we get
y = 6.34
c) If y = 9
[tex](9-16)/9 = -7*e^{(-0.016946*t)}[/tex]
Therefore we get the value of t is 129.66 years in 2055
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A paint manufacturer made a modification to a paint to speed up its drying time. Independent simple random samples of 11 cans of type A (the original paint) and 9 cans of type B (the modified paint) were selected and applied to similar surfaces. The drying times, in hours, were recorded.
The summary statistics are as follows.
Type A Type B
x1 = 76.3 hrs x2 = 65.1 hrs
s1 = 4.5 hrs s2 = 5.1 hrs
n1 = 11 n2 = 9
The following 98% confidence interval was obtained for μ1 - μ2, the difference between the mean drying time for paint cans of type A and the mean drying time for paint cans of type B:
4.90 hrs < μ1 - μ2 < 17.50 hrs
What does the confidence interval suggest about the population means?
Answer:
We can conclude that the drying time in hours for type A is significantly higher than the drying time for type B. And the margin above it's between 4.90 and 17.5 hours at 2% of significance.
Step-by-step explanation:
Previous concepts
A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".
The margin of error is the range of values below and above the sample statistic in a confidence interval.
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
[tex]\bar X_1 =76.3[/tex] represent the sample mean 1
[tex]\bar X_2 =65.1[/tex] represent the sample mean 2
n1=11 represent the sample 1 size
n2=9 represent the sample 2 size
[tex]s_1 =4.5[/tex] sample standard deviation for sample 1
[tex]s_2 =5.1[/tex] sample standard deviation for sample 2
[tex]\mu_1 -\mu_2[/tex] parameter of interest.
Confidence interval
The confidence interval for the difference of means is given by the following formula:
[tex](\bar X_1 -\bar X_2) \pm t_{\alpha/2}\sqrt{\frac{s^2_1}{n_1}+\frac{s^2_2}{n_2}}[/tex] (1)
The point of estimate for [tex]\mu_1 -\mu_2[/tex] is just given by:
[tex]\bar X_1 -\bar X_2 =76.3-65.1=11.2[/tex]
In order to calculate the critical value [tex]t_{\alpha/2}[/tex] we need to find first the degrees of freedom, given by:
[tex]df=n_1 +n_2 -1=11+9-2=18[/tex]
Since the Confidence is 0.98 or 98%, the value of [tex]\alpha=0.02[/tex] and [tex]\alpha/2 =0.01[/tex], and we can use excel, a calculator or a tabel to find the critical value. The excel command would be: "=-T.INV(0.01,18)".And we see that [tex]t_{\alpha/2}=\pm 2.55[/tex]
The standard error is given by the following formula:
[tex]SE=\sqrt{\frac{s^2_1}{n_1}+\frac{s^2_2}{n_2}}[/tex]
And replacing we have:
[tex]SE=\sqrt{\frac{4.5^2}{11}+\frac{5.1^2}{9}}=2.175[/tex]
Confidence interval
Now we have everything in order to replace into formula (1):
[tex]11.2-2.55\sqrt{\frac{4.5^2}{11}+\frac{5.1^2}{9}}=5.65[/tex]
[tex]11.2+2.55\sqrt{\frac{4.5^2}{11}+\frac{5.1^2}{9}}=16.75[/tex]
So on this case the 98% confidence interval would be given by [tex]5.65 \leq \mu_1 -\mu_2 \leq 16.75[/tex]
But let's assume that the confidence interval given is true 4.90 hrs < μ1 - μ2 < 17.50 hrs
What does the confidence interval suggest about the population means?
We can conclude that the drying time in hours for type A is significantly higher than the drying time for type B. And the margin above it's between 4.90 and 17.5 hours at 2% of significance.
The probability density function f(x) of a random variable X that has a uniform distribution between a and b is:
-(b + a)/2
-(a − b)/2
-1/b − 1/a
-None of these choices.
The probability density function (pdf) is;
f(x)=[tex]\frac{1}{b - a}[/tex] for a ≤ x ≤ b.
while the mean is given as [tex]\frac{a + b}{2}[/tex]
And the standard deviation given as [tex]\sqrt{\frac{(b - a)^{2} }{12} }[/tex]
Answer: -None of these choices.
PDF = 1/(b-a)
Step-by-step explanation:
The probability density function f(x) of a random variable X that has a uniform distribution between a and b is given by:
PDF = 1/(b-a) for X€[a,b]
otherwise zero.
Conduct a test at the a=0.05 level of significance by determining (a) null and alternative hypothesis, (b) the test statistic, (c) the P-value. Assume the samples were obtained independently from a large population using simple random sampling. Test whether p1 > p2. The sample data are x1=117 n1=249 x2=141 n2=312
Answer:
Since p > alpha, we accept H0, there is no evidence to prove that p1 is greater than p2
Step-by-step explanation:
Set up hypotheses as
[tex]H_0: p1 = p2\\H_a: p1>p2[/tex]
(Right tailed t test)
Alpha = 0.05
Sample I II Total
X 117 141 248
N 249 312 561
p 0.4700 0.4519 0.4420
p difference = 0.0181
Std dev = [tex]\sqrt{p(1-p)(\frac{1}{n_1} +\frac{1}{n_2} )}[/tex]
=0.0427
z statistic = 0.424
p value = 0.33724
Since p > alpha, we accept H0, there is no evidence to prove that p1 is greater than p2
Final answer:
To test whether p1 is greater than p2 using hypothesis testing, one needs to state the null and alternative hypotheses, calculate the test statistic and p-value, and then decide whether to reject or accept the null hypothesis based on the level of significance and the p-value. Calculating the test statistic and p-value requires specific formulas and is not provided here.
Explanation:
Conducting a Hypothesis Test for Two Population Proportions
A student would like assistance in conducting a hypothesis test for two population proportions. The steps to perform such a test include:
State the null and alternative hypotheses: The null hypothesis (H0) is that there is no difference between the two population proportions (p1 - p2 = 0), while the alternative hypothesis (Ha) posits that there is a difference (p1 > p2).
The random variable (P') represents the difference between the two sample proportions.
Calculate the test statistic: Using the provided sample sizes and successful outcomes, the test statistic is calculated using a formula based on the Z-distribution.
Calculate the p-value: The p-value is determined from the test statistic, indicating the probability of observing such a result if the null hypothesis were true.
At the 5 percent level of significance, compare the p-value to the alpha value of 0.05 to make a decision. If the p-value is less than alpha, reject the null hypothesis.
The Type I error would occur if the null hypothesis is incorrectly rejected when it is actually true.
The Type II error would occur if the null hypothesis is not rejected when it is actually false.
The test statistic and p-value cannot be calculated from the information provided without the appropriate formulas or statistical tools.
Decision Making and Errors
If the alpha level is greater than the p-value, the null hypothesis should be rejected, indicating there is evidence to suggest p1 is greater than p2.
Failure to reject the null hypothesis when it is false constitutes a Type II error.
Zener cards are often used to test the "psychic ability" of individuals. In the Zener deck, there are five different patterns displayed, and each has a 1/5 probability of being drawn from a well-shuffled deck. The five patterns are: circle, plus sign, wavy lines, empty box, and star. One hundred trials were conducted and your very impressive friend guessed right on 41 of those trials. Given this sample, can we use the normal approximation to the binomial?
Answer:
We need to check the conditions in order to use the normal approximation.
[tex]np=100*0.2=20 \geq 10[/tex]
[tex]n(1-p)=100*(1-0.2)=80 \geq 10[/tex]
If we check the conditions with the estimated proportion we got:
[tex]n\hat p=100*0.41=41 \geq 10[/tex]
[tex]n(1-\hat p)=100*(1-0.41)=59 \geq 10[/tex]
So we see that we satisfy the conditions and then we can apply the approximation.
Step-by-step explanation:
The binomial distribution is a "DISCRETE probability distribution that summarizes the probability that a value will take one of two independent values under a given set of parameters. The assumptions for the binomial distribution are that there is only one outcome for each trial, each trial has the same probability of success, and each trial is mutually exclusive, or independent of each other".
Let X the random variable of interest, on this case we now that:
[tex]X \sim Binom(n=100, p=0.2)[/tex]
The probability mass function for the Binomial distribution is given as:
[tex]P(X)=(nCx)(p)^x (1-p)^{n-x}[/tex]
Where (nCx) means combinatory and it's given by this formula:
[tex]nCx=\frac{n!}{(n-x)! x!}[/tex]
We need to check the conditions in order to use the normal approximation.
[tex]np=100*0.2=20 \geq 10[/tex]
[tex]n(1-p)=100*(1-0.2)=80 \geq 10[/tex]
If we check the conditions with the estimated proportion we got:
[tex]n\hat p=100*0.41=41 \geq 10[/tex]
[tex]n(1-\hat p)=100*(1-0.41)=59 \geq 10[/tex]
So we see that we satisfy the conditions and then we can apply the approximation.
a 62 year old man owns a non-tax qualified variable annuity. if this indvidual makes a lump-sum withdrawal from the plan, this would:
Answer:
If the 62 year old man makes a lump-sum withdrawal from the plan or tax structure, his investments would start incurring ordinary income taxes without attracting any other form of penalties. However, it has to be noted that prior to withdrawal of the lump-sum, his investments would grow without incurring income taxes.
The following questions refer to the CRT Technologies project selection example presented in this chapter. Formulate a constraint to implement the conditions described in each of the following statements. a. Out of projects 1, 2, 4, and 6, CRT’s management wants to select exactly two projects. b. Project 2 can be selected only if project 3 is selected and vice-versa. c. Project 5 cannot be undertaken unless both projects 3 and 4 are also undertaken. d. If projects 2 and 4 are undertaken, then project 5 must also be undertaken
This ensures that if both project 2 and project 4 are selected, project 5 must also be selected. Since x5 is a binary variable, 2x5 is equivalent to x5, ensuring that project 5 is selected when the condition is met. (option d)
Let's formulate constraints for each of the given statements:
a. Out of projects 1, 2, 4, and 6, CRT’s management wants to select exactly two projects.
Let [tex]\(x_i\)[/tex] be a binary decision variable representing whether project i is selected or not, where [tex]\(i = 1, 2, 4, 6\).[/tex]
The constraint can be formulated as:
[tex]\[x_1 + x_2 + x_4 + x_6 = 2\][/tex]
This ensures that exactly two out of the listed projects are selected.
b. Project 2 can be selected only if project 3 is selected and vice-versa.
Let [tex]\(x_2\) and \(x_3\)[/tex] be binary decision variables representing whether project 2 and project 3 are selected, respectively.
The constraints can be formulated as:
[tex]\[x_2 \leq x_3\]\[x_3 \leq x_2\][/tex]
These constraints ensure that if project 2 is selected, project 3 must also be selected, and vice versa.
c. Project 5 cannot be undertaken unless both projects 3 and 4 are also undertaken.
Let [tex]\(x_3\), \(x_4\), and \(x_5\)[/tex] be binary decision variables representing whether project 3, project 4, and project 5 are selected, respectively.
The constraint can be formulated as:
[tex]\[x_5 \leq x_3 + x_4\][/tex]
This ensures that if project 5 is selected, both project 3 and project 4 must also be selected.
d. If projects 2 and 4 are undertaken, then project 5 must also be undertaken.
Let [tex]\(x_2\), \(x_4\), and \(x_5\)[/tex] be binary decision variables representing whether project 2, project 4, and project 5 are selected, respectively.
The constraint can be formulated as:
[tex]\[x_2 + x_4 \leq 2x_5\][/tex]
Robin Inc. feared that the average company loss is running beyond $34,000. It initially conducted a hypothesis test on a sample extracted from its database. The hypothesis was formulated as H0: average company loss ≤ $34,000 H1: average company loss > $34,000. The test resulted in favor of Robin Inc.'s loss not exceeding $34,000. Detailed study of company accounts later revealed that the average company loss had run up to $37,896. Which of the following errors were made during the hypothesis test? Select one: a) Type III error b) Type II error c) Type I error d) Type IV error
Answer
b. Type II error
Step-by-step explanation:
The hypothesis was formulated as
the solution can be seen in the attached document
There is a strong correlation between the temperature and the number of skinned knees on playgrounds. Does this tell us that warm weather causes children to trip? Choose the correct answer below. A. Yes. In warm weather, more children will go outside and play. B. No. Warm weather will cause less children to trip and suffer skinned knees. C. No. In warm weather, more children will go outside and play. D. Yes. Warm weather will cause more children to trip and suffer skinned knees.
Answer:
C. No. In warm weather, more children will go outside and play
Step-by-step explanation:
The correct answer is option C: No. In warm weather, more children will go outside and play.
Correlation means that two variables are related, but it does not necessarily mean that one causes the other. In this case, there is a strong correlation between temperature and the number of skinned knees on playgrounds, but it does not tell us that warm weather causes children to trip.
Option A is incorrect because warm weather does not directly cause children to go outside and play. It may be a factor, but it is not the sole reason. Option B is incorrect because warm weather does not cause fewer children to trip and suffer skinned knees. In fact, the correlation suggests that more children are likely to be outside playing in warm weather, which could potentially increase the number of skinned knees. Option D is incorrect because warm weather does not directly cause more children to trip and suffer skinned knees.
The correlation suggests that the increase in skinned knees is likely due to more children being outside and playing, rather than the warm weather itself. To summarize, the strong correlation between temperature and the number of skinned knees on playgrounds indicates that in warm weather, more children will go outside and play. However, it does not tell us that warm weather causes children to trip.
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A continuous random variable may assume:
-any value in an interval or collection of intervals
-only integer values in an interval or collection of intervals
-only fractional values in an interval or collection of intervals
-only the positive integer values in an interval
Answer:
-any value in an interval or collection of intervals
Step-by-step explanation:
Discrete random variables are only integers in the interval.
Continuous random variables are all the values(integers, fractional, negative, positive) in an interval, or a collection of intervals.
The correct answer is:
-any value in an interval or collection of intervals
A continuous random variable can assume any value in an interval or collection of intervals. Unlike discrete random variables, which can only take integer values, continuous variables can take a range of values, like measurements such as height.
Explanation:A continuous random variable is a type of variable in statistics that can assume any value within an interval or collection of intervals. This is different from a discrete random variable which can only take on a finite or countable number of values (often integer values).
For example, if we measure the height of a person, it could be any value within the feasible range, say between 0 meter and 3 meters. This is a continuous variable because there are infinite possibilities between 0 and 3, including measurements like 1.73 meters or 2.45 meters etc. It's not limited to integer values (like 1 m, 2 m, etc.), nor only fractional values, nor just positive integers within an interval.
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Compare - 40% of A is equal to $300 and 30% of B is equal to $400
Answer:
B is greater than A.
Step-by-step explanation:
We have been given that 40% of A is equal to $300 and 30% of B is equal to $400. We are asked to compare both quantities.
Let us find A and B using our given information.
[tex]\frac{40}{100}*A=300[/tex]
[tex]0.40A=300[/tex]
[tex]\frac{0.40A}{0.40}=\frac{300}{0.40}[/tex]
[tex]A=750[/tex]
Similarly, we will find B.
[tex]\frac{30}{100}*B=400[/tex]
[tex]0.30*B=400[/tex]
[tex]\frac{0.30B}{0.30}=\frac{400}{0.30}[/tex]
[tex]B=1333.3333[/tex]
We know that smaller percent of big number is greater than bigger percent of a small number.
Therefore, B is greater than A.
Answer:
Step-by-step explanation:
40% Of A = 300
30% of B = 400
40a / 100 = 300, 40a = 3 divide both sides by 3 ,
then a = 13.33 approximately 13
30b = 400 = 400, 30b = 4 divide both sides by 30, then b =7.5
comparing both results where a = 13 , b = 7.5
a is greater than b with difference of 5.5
Solve the following equation. log Subscript 2 Baseline (3 x plus 7 )equals 5 The solution set is StartSet nothing EndSet . (Simplify your answer.)
Answer: [tex]x=\dfrac{25}{3}[/tex]
Step-by-step explanation:
The given equation : [tex]\log_2(3x+7)=5[/tex]
Using logarithmic property : [tex]\log_a N=M\to N=a^M[/tex]
The given equation will be equivalent to [tex](3x+7)=2^5[/tex]
[tex]\Rightarrow\ 3x+7=32[/tex]
Subtract 7 from both sides , we get
[tex]3x=25[/tex]
Divide both sides by 3 , we get
[tex]x=\dfrac{25}{3}[/tex]
Hence, the solution is [tex]x=\dfrac{25}{3}[/tex]
Some sources report that the weights of full-term newborn babies in a certain town have a mean of 7 pounds and a standard deviation of 1.2 pounds and are normally distributed.a. What is the probability that one newborn baby will have a weight within 1.2 pounds of the meanlong dashthat is, between 5.8 and 8.2 pounds, or within one standard deviation of the mean?b. What is the probability that the average of nine babies' weights will be within 1.2 pounds of the mean; will be between 5.8 and 8.2 pounds?c. Explain the difference between (a) and (b).
Answer:
a) [tex]P(5.8<X<8.2)=P(\frac{5.8-7}{1.2}<Z<\frac{8.2-7}{1.2})=P(-1<Z<1)=P(Z<1)-P(Z<-1)=0.841-0.159=0.683[/tex]
b) [tex]P(5.8<\bar X <8.2) = P(Z<3)-P(Z<-3)=0.999-0.0014=0.9973[/tex]
c) For part a we are just finding the probability that an individual baby would have a weight between 5.8 and 8.2. So we can't compare the result of part a with the result for part b.
For part b we are finding the probability that the mean of 9 babies (from random sampling) would be between 5.8 and 8.2, so on this case we have a distribution with a different deviation depending on the sample size. And for this reason we have different values
Step-by-step explanation:
Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".
The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean". The letter [tex]\phi(b)[/tex] is used to denote the cumulative area for a b quantile on the normal standard distribution, or in other words: [tex]\phi(b)=P(z<b)[/tex]
Let X the random variable that represent the weights of full-term newborn babies of a population, and for this case we know the distribution for X is given by:
[tex]X \sim N(7,1.2)[/tex]
a. What is the probability that one newborn baby will have a weight within 1.2 pounds of the meanlong dashthat is, between 5.8 and 8.2 pounds, or within one standard deviation of the mean?
We are interested on this probability
[tex]P(5.8<X<8.2)[/tex]
And the best way to solve this problem is using the normal standard distribution and the z score given by:
[tex]Z=\frac{x-\mu}{\sigma}[/tex]
If we apply this formula to our probability we got this:
[tex]P(5.8<X<8.2)=P(\frac{5.8-\mu}{\sigma}<\frac{X-\mu}{\sigma}<\frac{8.2-\mu}{\sigma})[/tex]
And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.
[tex]P(5.8<X<8.2)=P(\frac{5.8-7}{1.2}<Z<\frac{8.2-7}{1.2})=P(-1<Z<1)=P(Z<1)-P(Z<-1)=0.841-0.159=0.683[/tex]
b. What is the probability that the average of nine babies' weights will be within 1.2 pounds of the mean; will be between 5.8 and 8.2 pounds?
And let [tex]\bar X[/tex] represent the sample mean, the distribution for the sample mean is given by:
[tex]\bar X \sim N(\mu,\frac{\sigma}{\sqrt{n}})[/tex]
On this case [tex]\bar X \sim N(7,\frac{1.2}{\sqrt{9}})[/tex]
The z score on this case is given by this formula:
[tex]z=\frac{\bar x-\mu}{\frac{\sigma}{\sqrt{n}}}[/tex]
And if we replace the values that we have we got:
[tex]z_1=\frac{5.8-7}{\frac{1.2}{\sqrt{9}}}=-3[/tex]
[tex]z_2=\frac{8.2-7}{\frac{1.2}{\sqrt{9}}}=3[/tex]
For this case we can use a table or excel to find the probability required:
[tex]P(5.8<\bar X <8.2) = P(Z<3)-P(Z<-3)=0.999-0.0014=0.9973[/tex]
c. Explain the difference between (a) and (b).
For part a we are just finding the probability that an individual baby would have a weight between 5.8 and 8.2. So we can't compare the result of part a with the result for part b.
For part b we are finding the probability that the mean of 9 babies (from random sampling) would be between 5.8 and 8.2, so on this case we have a distribution with a different deviation depending on the sample size. And for this reason we have different values
A numerical description of the outcome of an experiment is called a
a. descriptive statistic.
b. probability function.
c. variance.
d. random variable.
Answer: d. random variable.
Step-by-step explanation:
A random variable is a numerical description of outcomes of an experiment, it can be used to represent the possible values of a past experiment or yet-to-be-performed experiments. It is a variable whose values depends on outcome of a random occurrence. Random variables also allows the calculation of probability of an occurrence or result in a particular experiment.
The numerical description of the outcome of an experiment is best described as a random variable. It is not referred to as a descriptive statistic, a probability function, or variance.
Explanation:In statistics, a numerical description of the outcome of an experiment is referred to as a random variable. The term random variable refers to a function that assigns a real number to each outcome of an experiment conducted according to a certain probability distribution. This term is central to probability theory and statistics, in which numerical results of random variables are analyzed to understand underlying processes or to make predictions.
On the other hand, descriptive statistics summarize and organize characteristics of a data set. A probability function is a mathematical function that provides the probabilities of occurrence of different possible outcomes. Variance is a measurement of spread between numbers in a data set.
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This question is to show that we can `recode' and model a situation that depends on nitely many past states as a homogeneous Markov chain. Suppose we model the daily weather as a Markov chain. The weather has just two states: cloudy and sunny. Suppose that if it is sunny today and was sunny yesterday then it will be sunny tomorrow with probability 0:6; if sunny today but cloudy yesterday then it will be sunny tomorrow with probability 0:5; if cloudy today but sunny yesterday then it will be sunny tomorrow with probability 0:4; if it was cloudy for the last two days then it will be sunny tomorrow with probability 0:2. Calculate the expected fraction of cloudy days.
Answer:
F=y+z=4/6.25
Step-by-step explanation:
First, we have to consider that in the problem model we have only two possible states: sunny and cloudy. Now, according to the information given in the statement, we also have the behavior of the last two days. In any case, we can have four possible transitional states:
Today-Yesterday(S=Sunny, C=cloudy)
1) ST and SY (Sunny today and sunny yesterday)
2) ST and CY.
3) CT and SY.
4) CT and CY.
Now, according to the statement, the probabilities given for the four states can be expressed by the following matrix:
[tex]\left[\begin{array}{cccc}0.6&0&(1-0.6)&0\\0.5&0&(1-0.5)&0\\0&0.4&0&(1-0.4)\\0&0.2&0&(1-0.2)\end{array}\right][/tex]
Now, making w, x, y, z as the transition probabilities for the four states mentioned, we then have that:
x=0.6w+0.5x
w=1.25x (1)
x=0.4y+0.2z (2)
y=0.4w+0.5x
y= 0.4(1.25x)+0.5x=x
y=x (3)
replacing 3 in 2:
y=0.4y+0.2x
x=3y (4)
And as w+x+y+z= 1 (no more possible combinations):
w+x+y+z=1 (5)
So, replacing the expressions obtained previously in equation 5, we have finally that:
1.25x+x+x+3x=1
x=1/6.25=y
z=3x=3/6.25
So, the fraction of sunny days is given by:
F=y+z=4/6.25
Assume a device manufacturer tests 100 devices. The first device fails at 100 hours. The last device fails at 200 hours. What is the device MTBF:a. 10,000 Hoursb. 15,000 hours c. 20,000 hours d. 100 hours
Answer:
a. 10,000 Hours
Step-by-step explanation:
MTBF (Mean Time Between Failures) can be calculated using the formula:
[tex]MTBF={(L-F)}*{n}[/tex] where
L is the time at which last device fails (200 hours) F is the time at which first device fails (100 hours) n is the number of devices tested (100)[tex]{MTBF=(200-100)}*{100}=10000[/tex]
Final answer:
The MTBF for a set of devices tested by the manufacturer, with failures evenly distributed from 100 to 200 hours, is 15,000 hours, which is calculated using the sum of an arithmetic series formula.
Explanation:
The student is asking about the mean time between failures (MTBF) for a set of devices. MTBF is a basic measure of reliability for repairable items and represents the average time expected between failures. To calculate MTBF, you divide the total operational time by the number of failures. In this case, the device manufacturer tests 100 devices, with the first failing after 100 hours and the last after 200 hours, which suggests a linear distribution of failures over time.
Assuming a linear and even distribution of failures from 100 to 200 hours for the 100 devices, you would calculate the total operational time before each device failed and then divide by the number of devices. The calculation would be the sum of an arithmetic series:
MTBF = (100 hours + 101 hours + ... + 200 hours) / 100 devices
We can use the formula for the sum of an arithmetic series:
S = n/2 * (a1 + an)
Where:
n is the number of terms in the series (here, 100 devices),
a1 is the first term in the series (100 hours),
an is the last term in the series (200 hours),
Now apply the formula:
MTBF = 100/2 * (100 + 200)
MTBF = 50 * 300
MTBF = 15,000 hours
So, the answer is b. 15,000 hours.
PLEASE HELP ME!!!
What transformations are represented by the following coordinate graphing? (geometry)
(a,b) --> (a,-b)
(a,b) --> (a, b+5)
(a,b) --> (b,-a)
Step-by-step explanation:
(a, b) → (a, -b)
This is a reflection across the x-axis.
(a, b) → (a, b+5)
This is a translation 5 units up.
(a, b) → (b, -a)
This is a rotation of 270° about the origin.
What is the selling price of merchandise listed at $5,900 if discounts of 15%, 10%, and 4% are given?
Answer:
after 15%, discount = $5,015
after 10%, discount = $5,310
after 4%, discount= $5,664
Step-by-step explanation:
1.discount of 15 % of the price listed
so 15 % of $5,900 will be= 15/100 x 5900 = 885 $
so after discounting the price =$5,900 - $885 = $5,015
2. discount of 10 % of the price listed
so 10 % of $5,900 will be= 10/100 x 5900 = 590 $
so after discounting the price =$5,900 - $590 = $5,310
3. discount of 4 % of the price listed
so 4 % of $5,900 will be= 4/100 x 5900 = 236 $
so after discounting the price =$5,900 - $236 = $5,664
The cash operating expenses of the regional phone companies during the first half of 1994 were distributed about a mean of $29.93 per access line per month, with a standard deviation of $2.65. Company A's operating expenses were $27.00 per access line per month. Assuming a normal distribution of operating expenses, estimate the percentage of regional phone companies whose operating expenses were closer to the mean than the operating expenses of Company A were to the mean. (Round your answer to two decimal places.)
Answer:
The percentage of regional phone companies whose operating expenses were closer to the mean than the operating expenses of Company A were to the mean is 73%.
Step-by-step explanation:
The Company A's operating expenses were $27.00. This is $2.93 less than the regional mean.
[tex]\Delta E=29.93-27.00=2.93[/tex]
The companies whose operating expenses are closer to the mean are the ones that have expenses $2.93 below or above the mean.
The fraction of companies that are closer to the mean is equal to the proability of having expenses between those two limits:
[tex]z_1=(M-\mu)/\sigma=-2.93/2.65=-1.105\\\\z_2=+1.105[/tex]
[tex]P(|z|\leq1.105)=P(z\leq 1.105)-P(z<-1.105)=0.86542-0.13458=0.73[/tex]
To find the percentage of companies with operating expenses closer to the mean than Company A, calculate the Z score for Company A. Then find the percentile, and double it to account for both sides of the normal distribution.
Explanation:To find out the percentage of regional phone companies that had operating expenses closer to the mean than the ones of Company A, we need to calculate the Z-score for Company A. The
Z-score
is a measure of how many standard deviations an element is from the mean. In this particular case, you can calculate the Z score using the formula:
Z = (X - μ) / σ
, where X is the value from the dataset (in this case, Company A's operating expenses), μ is the mean of the dataset, and σ is the standard deviation of the dataset.
So using the data from the question:
Z = ($27.00 - $29.93) / $2.65 = -1.109. Next, recognize that finding the percentage closer to the mean is the same as finding the percentile of company A's Z-score. You can then use a standard normal distribution table or online Z-score calculator to find the percentile associated with a Z-score of -1.109. If it's a two-tailed test (as normally implied by the word 'closer' in statistical analysis), you can multiply the cumulative probability by 2, as it would be the probability on either side of the distribution.This will give you a percentage that can be understood as the percentage of regional phone companies which had operating expenses closer to the mean than Company A's were to the mean.
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A fisherman catches fish according to a Poisson process with rate lambda = 0.6 per hour. The fisherman will keep fishing for two hours. At the end of the second hour, if he has caught at least one fish, he quits; Otherwise, he continues until he catches one fish. (a) Find the probability that he stays for more than two hours. (b) Find the probability that the total time he spends fishing is between two and five hours. (c) Find the expected number offish that he catches. (d) Find the expected total fishing time, given that he has been fishing for four hours.
The probability that the fisherman stays for more than two hours is approximately 0.4512. The probability that the total time the fisherman spends fishing is between two and five hours is approximately 0.5043. The expected number of fish that the fisherman catches is 0.6.
Explanation:To solve this problem, we can use the concept of a Poisson process and the properties of the Poisson distribution.
(a) We want to find the probability that the fisherman stays for more than two hours. Since the fisherman quits at the end of the second hour if he has caught at least one fish, he will stay for more than two hours only if he hasn't caught any fish in the first two hours. Using the Poisson distribution, the probability of catching zero fish in two hours is given by P(X=0)=e^(-lambda*t)*(lambda^0)/(0!)=e^(-0.6*2)≈0.5488. Therefore, the probability that the fisherman stays for more than two hours is 1 - P(X=0) = 1 - 0.5488 ≈ 0.4512.
(b) The total time the fisherman spends fishing can be between two and five hours. This can happen in three ways: fishing for 2 hours without catching fish (P(X=0)) and then fishing for 3 more hours until catching the first fish (P(X=1)); fishing for 3 hours without catching fish (P(X=0)) and then fishing for 2 more hours until catching the first fish (P(X=1)); fishing for 4 hours without catching fish (P(X=0)) and then fishing for 1 more hour until catching the first fish (P(X=1)). Using the Poisson distribution, we can calculate the probabilities for each case: P(X=0) = e^(-0.6*2) ≈ 0.5488, P(X=1) = e^(-0.6*3)*(0.6^1)/(1!) ≈ 0.3293. Adding up these probabilities, we get P(X=0)*P(X=1) + P(X=0)*P(X=1) + P(X=0)*P(X=1) = 0.5488*0.3293 + 0.5488*0.3293 + 0.5488*0.3293 ≈ 0.5043. Therefore, the probability that the total time the fisherman spends fishing is between two and five hours is approximately 0.5043.
(c) The expected number of fish that the fisherman catches can be found using the formula for the mean of a Poisson distribution, which is equal to the rate parameter lambda. In this case, lambda = 0.6, so the expected number of fish is 0.6.
(d) To find the expected total fishing time given that the fisherman has been fishing for four hours, we need to condition on the event that the fisherman hasn't caught any fish in the first four hours. Using the Poisson distribution, the probability of catching zero fish in four hours is given by P(X=0) = e^(-lambda*t)*(lambda^0)/(0!) = e^(-0.6*4) ≈ 0.3012. Therefore, the expected total fishing time given that the fisherman has been fishing for four hours is 4 + (1/P(X=0)) = 4 + (1/0.3012) ≈ 7.32 hours.
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