Question 1

Forty-nine items are randomly selected from a population of 200 items. The sample mean is 30 and the sample standard deviation is 16. What is the 99 percent confidence interval for the population mean?

Accepted Answer

The answer of Forty-nine items are randomly selected from a...

Question 2

A survey of households in a small town showed that in 500 of 1,200 sampled households, at least one member attended a town meeting during the year. Using the 95% level of confidence, what is the confidence interval for the proportion of households represented at a town meeting?

Accepted Answer

A)  [0.417, 0.427] 
B)  [0.389, 0.445] 
C)  [0.400, 0.417] 
D)  [0.417, 0.445]

Question 3

Increasing sample sizes result in _______________ interval estimates of a population parameter.

Accepted Answer

The answer of Increasing sample sizes result in _______________ interval...

Question 4

A survey of 50 retail stores revealed that the average price of a microwave was $375 with a sample standard deviation of $20. Assuming the population is normally distributed, what is the 99% confidence interval to estimate the true cost of the microwave?

Accepted Answer

A)  $367.42 to $382.58 
B)  $315.00 to $415.00 
C)  $323.40 to $426.60 
D)  $335.82 to $414.28

Question 5

A confidence interval for a population proportion uses the uniform distribution to approximate the binomial distribution.

Accepted Answer

A) True 
 B)False

Question 6

A survey of an urban university (population of 25,450) showed that 750 of 1,100 students sampled attended a home football game during the season. Using the 90% level of confidence, what is the confidence interval for the proportion of students attending a football game?

Accepted Answer

A)  [0.7510, 0.8290] 
B)  [0.6591, 0.7045] 
C)  [0.6659, 0.6941] 
D)  [0.6795, 0.6805]

Question 7

Explain the concept of a confidence interval when estimating a population mean.

Accepted Answer

The answer of Explain the concept of a confidence interval...

Question 8

Which of the following is NOT necessary to determine how large a sample to select from a population?

Accepted Answer

A)  The level of confidence in estimating the population parameter 
B)  The size of the population 
C)  The maximum allowable error in estimating the population parameter 
D)  An estimate of the population variation

Question 9

To calculate the sample size required to estimate a population mean, we must know or estimate the ______________ of the population distribution.

Accepted Answer

The answer of To calculate the sample size required to...

Question 10

A point estimate is a single value used to estimate a population parameter.

Accepted Answer

A) True 
 B)False

Question 11

A university wants to determine the proportion of students who use a cash card to pay at the university food service. Out of 100 students surveyed, 65 students use a cash card. Estimate the value of the population proportion.

Accepted Answer

The answer of A university wants to determine the proportion...

Question 12

A survey of an urban university (population of 25,450) showed that 870 of 1,100 students sampled supported a fee increase to fund improvements to the student recreation center. Using the 95% level of confidence, what is the confidence interval for the proportion of students supporting the fee increase?

Accepted Answer

A)  [0.767, 0.815] 
B)  [0.759, 0.822] 
C)  [0.771, 0.811] 
D)  [0.714, 0.866]

Question 13

A local grocery store wants to estimate the mean daily number of gallons of milk sold to customers. Assume the number of gallons sold follows the normal distribution, with a population standard deviation of 5.10 gallons. A random sample of 60 days shows that the mean daily number of gallons sold is 10.00. Compute a 99% confidence interval for the population mean.

Accepted Answer

The answer of A local grocery store wants to estimate...

Question 14

The Nile Superstore is conducting a survey of consumer preferences for a new wireless e-book reader. A sample of 160 people reveals that 120 would buy the new reader. Estimate the value of the population proportion.

Accepted Answer

The answer of The Nile Superstore is conducting a survey...

Question 15

A survey of 25 grocery stores revealed that the mean price of a gallon of milk was $2.98, with a standard error of $0.10. What is the 95% confidence interval to estimate the true cost of a gallon of milk?

Accepted Answer

A)  $2.81 to $3.15 
B)  $2.94 to $3.02 
C)  $2.77 to $3.19 
D)  $2.95 to $3.01

Question 16

The mean number of travel days per year for salespeople employed by three hardware distributors needs to be estimated with a 0.90 degree of confidence. For a small pilot study, the mean was 150 days and the standard deviation was 14 days. If the population mean is estimated within two days, how many salespeople should be sampled?

Accepted Answer

A)  133 
B)  452 
C)  511 
D)  2,100

Question 17

A sample standard deviation is the best point estimate of the ___________.

Accepted Answer

A)  population range 
B)  population skewness 
C)  population mode 
D)  population standard deviation

Question 18

An interval estimate is a range of values used to estimate a population parameter.

Accepted Answer

A) True 
 B)False

Question 19

Assuming a normal population with a known population standard deviation, the z statistic for a 99% confidence interval would be ______.

Accepted Answer

The answer of Assuming a normal population with a known...

Question 20

A confidence interval becomes narrower when the sample size _________.

Accepted Answer

The answer of A confidence interval becomes narrower when the...

Exam 9: Estimation and Confidence Intervals

Forty-nine items are randomly selected from a population of 200 items. The sample mean is 30 and the sample standard deviation is 16. What is the 99 percent confidence interval for the population mean?

A survey of households in a small town showed that in 500 of 1,200 sampled households, at least one member attended a town meeting during the year. Using the 95% level of confidence, what is the confidence interval for the proportion of households represented at a town meeting?

Increasing sample sizes result in _______________ interval estimates of a population parameter.

A survey of 50 retail stores revealed that the average price of a microwave was $375 with a sample standard deviation of $20. Assuming the population is normally distributed, what is the 99% confidence interval to estimate the true cost of the microwave?

A confidence interval for a population proportion uses the uniform distribution to approximate the binomial distribution.

A survey of an urban university (population of 25,450) showed that 750 of 1,100 students sampled attended a home football game during the season. Using the 90% level of confidence, what is the confidence interval for the proportion of students attending a football game?

Explain the concept of a confidence interval when estimating a population mean.

Which of the following is NOT necessary to determine how large a sample to select from a population?

To calculate the sample size required to estimate a population mean, we must know or estimate the ______________ of the population distribution.

A point estimate is a single value used to estimate a population parameter.

A university wants to determine the proportion of students who use a cash card to pay at the university food service. Out of 100 students surveyed, 65 students use a cash card. Estimate the value of the population proportion.

The Nile Superstore is conducting a survey of consumer preferences for a new wireless e-book reader. A sample of 160 people reveals that 120 would buy the new reader. Estimate the value of the population proportion.

A survey of 25 grocery stores revealed that the mean price of a gallon of milk was $2.98, with a standard error of $0.10. What is the 95% confidence interval to estimate the true cost of a gallon of milk?

A sample standard deviation is the best point estimate of the ___________.

An interval estimate is a range of values used to estimate a population parameter.

Assuming a normal population with a known population standard deviation, the z statistic for a 99% confidence interval would be ______.

A confidence interval becomes narrower when the sample size _________.