Let X1,X2,X3,and X4 be a random sample of observations from a population with mean μ and variance σ2.Consider the following estimator of μ: 1 = 0.15 X1 + 0.35 X2 + 0.20 X3 + 0.30 X4.What is the variance of 1?

A) 0)20 σ2 B) 0)275 σ2 C) 0)55 σ2 D) 0)125 σ2 A) 0)20 σ2 B) 0)275 σ2 C) 0)55 σ2 D) 0)125 σ2

Exam 7: Estimation: Single Population

A sample of 50 students is taken from Utah Valley University (UVU).These students spent an average of $175 on books this semester,with a standard deviation of $25.A 95% confidence interval for the average amount of money spent on books for all students at UVU is equal to ________.(Hint: Use Excel function to obtain the critical value. )

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Question 1

Correct Answer:

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THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The Daytona Beach Tourism Commission is interested in the average amount of money a typical college student spends per day during spring break.They survey 35 students and find that the mean spending is $63.57 with a standard deviation of $17.32. -What level of confidence is associated with an interval of $58.62 to $68.52 for the population mean daily spending?

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Question 2

Correct Answer:

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t_n_-1,_α_/2 s/
= (68.52 - 58.62)/ 2 = 4.95 ⇒ t_34,_α_/2

= 4.95 ⇒ t_34,_α_/2 = 1.69.
Hence,α/2 = 0.05,or α = 0.10.Then the confidence level is 90%.

Find the upper confidence limit of the 90% confidence interval.

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Question 3

Correct Answer:

Verified

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: Suppose that the waiting times for patients at a local hospital are normally distributed with known population standard deviation of 30 minutes.A random sample of 75 patients in the local hospital had a mean time of 90 minutes.Assume a 95% confidence interval for the population mean μ. -Calculate the margin of error of the 95% confidence interval.

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Question 4

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The number of beverage cans produced each hour from a vending machine is normally distributed with a standard deviation of 8.6.For a random sample of 12 hours,the average number of beverage cans produced was 326.0.Assume a 99% confidence interval for the population mean number of beverage cans produced per hour. -Calculate the margin of error of the 99% confidence interval.

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Question 5

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A clinic offers a weight-reduction program.A review of its records revealed the following weight losses,in pounds,for a random sample of 10 of its clients at the conclusion of the program: 20,15,21,28,22,19,9,14,18,and 23. -Find a 95% confidence interval for the population mean.

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Question 6

The t-distribution with n -1 degrees of freedom is often used to construct confidence intervals of the population mean when the population standard deviation is known.

(True/False)

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Question 7

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A school bus driver records the time (in minutes)it takes to commute to school for six days.Those results are: 25,22,17,20,15,and 10.Assuming the population is normally distributed,develop a 90% confidence interval for the population mean. -Determine the reliability factor from the Student's t distribution table.

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Question 8

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A regional CPA firm conducted an audit for a discount chain.One part of the audit involved developing an estimate for the mean dollar error in total charges that occur during the checkout process.They wish to develop a 90% confidence interval estimate for the population mean.A simple random sample of n = 20 is selected,with the following data (in dollars): -Calculate the sample standard deviation.

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Question 9

If a sample of size 200 has 40 successes,the lower limit of a confidence interval at the 95% level of confidence for the population proportion is:

(Multiple Choice)

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Question 10

In a recent survey of 574 employees,15.5% indicated that they were not in favor of a particular plan.What is the level of confidence associated with the interval of 12.85% to 19.89%?

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Question 11

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A researcher is interested in determining the percentage of all households in the U.S.that have more than one home computer.In a survey of 492 households,27% indicated that they own more than one home computer. -The researcher reports a confidence interval of 0.2312 to 0.3096 but neglects to tell you the confidence level.What is the confidence level associated with this interval?

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Question 12

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A random sample of ten homes in a particular suburb had the following selling prices (in thousands of dollars): 92,83,110,115,108,96,102,90,100,and 98. -Find a point estimate of the population mean that is unbiased and efficient.

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Question 13

Let X₁,X₂,X₃,and X₄ be a random sample of observations from a population with mean μ and variance σ².Consider the following estimator of μ: ₁ = 0.15 X₁ + 0.35 X₂ + 0.20 X₃ + 0.30 X₄.What is the variance of ₁?

(Multiple Choice)

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Question 14

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A clinic offers a weight-reduction program.A review of its records revealed the following weight losses,in pounds,for a random sample of 10 of its clients at the conclusion of the program: 20,15,21,28,22,19,9,14,18,and 23. -How large the sample is needed to estimate the population proportion if ME = 0.09,a = 0.05?

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Question 15

If a sample of size 61 is selected,the value of A for the probability P(-A ≤ t ≤A)= 0.95 is:

(Multiple Choice)

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Question 16

A sample statistic such that the mean of all its possible values equals the population parameter the statistic seeks to estimate is an unbiased estimator.

(True/False)

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Question 17

For a 90% confidence interval,the reliability factor is equal to 1.96.

(True/False)

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Question 18

Which of the following statements is true regarding the width of a confidence interval for a population proportion?

(Multiple Choice)

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Question 19

A 95% confidence interval for the population proportion will not extend approximately 1.96 on each side of the sample proportion.

(True/False)

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Question 20

Showing 1 - 20 of 151

Find the upper confidence limit of the 90% confidence interval.

The t-distribution with n -1 degrees of freedom is often used to construct confidence intervals of the population mean when the population standard deviation is known.

If a sample of size 200 has 40 successes,the lower limit of a confidence interval at the 95% level of confidence for the population proportion is:

In a recent survey of 574 employees,15.5% indicated that they were not in favor of a particular plan.What is the level of confidence associated with the interval of 12.85% to 19.89%?

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A random sample of ten homes in a particular suburb had the following selling prices (in thousands of dollars): 92,83,110,115,108,96,102,90,100,and 98. -Find a point estimate of the population mean that is unbiased and efficient.

Let X₁,X₂,X₃,and X₄ be a random sample of observations from a population with mean μ and variance σ².Consider the following estimator of μ: ₁ = 0.15 X₁ + 0.35 X₂ + 0.20 X₃ + 0.30 X₄.What is the variance of ₁?

If a sample of size 61 is selected,the value of A for the probability P(-A ≤ t ≤A)= 0.95 is:

A sample statistic such that the mean of all its possible values equals the population parameter the statistic seeks to estimate is an unbiased estimator.

For a 90% confidence interval,the reliability factor is equal to 1.96.

Which of the following statements is true regarding the width of a confidence interval for a population proportion?

A 95% confidence interval for the population proportion will not extend approximately 1.96 on each side of the sample proportion.

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