Question 1

A research firm conducted a survey to determine the mean amount people spend at a popular coffee shop during a week. They found the amounts spent per week followed a normal distribution, with a population standard deviation of $4. A sample of 49 customers revealed that the mean is $25. What is the 95% confidence interval estimate of µ?

Accepted Answer

The answer of A research firm conducted a survey to...

Question 2

A finite population correction factor is used to adjust the _________________.

Accepted Answer

The answer of A finite population correction factor is used...

Question 3

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 4

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 5

A company's headquarters is located in downtown Chicago. If they require their employees to start working at 6:00 a.m., the company is interested to know the mean driving time of its employees. Fifty employees are randomly sampled over four weeks and asked to record their driving times. The mean driving time is 35 minutes, with a standard deviation of 10 minutes. What is the 98% confidence interval for the population mean?

Accepted Answer

The answer of A company's headquarters is located in downtown...

Question 6

A survey of 16 executives showed a mean work time per week of 50 hours, with a standard deviation of 10 hours. What is the 95% confidence interval for the population mean?

Accepted Answer

The answer of A survey of 16 executives showed a...

Question 7

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the 95% confidence interval for the proportion defective?

Accepted Answer

The answer of A silkscreen printing company purchases t-shirts. To...

Question 8

Sugar is packaged in 16-ounce bags. To test the weight of the bags, a few were checked. The mean weight was 15.95 ounces and the standard deviation was 0.5 ounces. How many bags must the processor sample to be 99% confident that the sample mean does not differ from the population mean by more than 0.2 ounces?

Accepted Answer

The answer of Sugar is packaged in 16-ounce bags. To...

Question 9

A consultant is planning a survey of corporate executives to determine their mean amount of weekly work time. A pilot survey indicated that the mean work time per week is 50 hours, with a standard deviation of 10 hours. The consultant wants to estimate the mean weekly work time within five hours. The 95% level of confidence is to be used. How many executives should be surveyed?

Accepted Answer

The answer of A consultant is planning a survey of...

Question 10

A research firm conducted a survey to determine the mean amount people spend at a popular coffee shop during a week. They found the amounts spent per week followed a normal distribution with a population standard deviation of $4. A sample of 64 customers revealed that the mean is $25. What is the 99% confidence interval estimate of µ?

Accepted Answer

The answer of A research firm conducted a survey to...

Question 11

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. What is the 99% confidence interval for the population proportion?

Accepted Answer

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

Question 12

The estimate of the population proportion is to be within plus or minus .10, with a 95% level of confidence. The best estimate of the population proportion is .25. How large a sample is required?

Accepted Answer

The answer of The estimate of the population proportion is...

Question 13

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the estimated proportion defective in the population?

Accepted Answer

The answer of A silkscreen printing company purchases t-shirts. To...

Question 14

We want to estimate the population mean of waiting time in a doctor's office within 20 minutes, with a 99% level of confidence. The population standard deviation is estimated to be 15. How large a sample is required?

Accepted Answer

The answer of We want to estimate the population mean...

Question 15

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. What is the point estimate of the population mean?

Accepted Answer

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

Question 16

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. What is the 95% confidence interval for the population proportion?

Accepted Answer

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

Question 17

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 18

A population has a standard deviation of 25. We want to estimate the population mean within 2, with a 95% level of confidence. How large a sample is required?

Accepted Answer

The answer of A population has a standard deviation of...

Question 19

A local health care company wants to estimate the mean weekly elder day-care cost. A sample of 10 facilities shows a mean of $250 per week, with a standard deviation of $25. What is the 90% confidence interval for the population mean?

Accepted Answer

The answer of A local health care company wants to...

Question 20

A finite population correction factor is used when we know the _________________.

Accepted Answer

The answer of A finite population correction factor is used...

Quiz 9: Estimation and Confidence Intervals

A finite population correction factor is used to adjust the _________________.

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 16 executives showed a mean work time per week of 50 hours, with a standard deviation of 10 hours. What is the 95% confidence interval for the population mean?

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the 95% confidence interval for the proportion defective?

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. What is the 99% confidence interval for the population proportion?

The estimate of the population proportion is to be within plus or minus .10, with a 95% level of confidence. The best estimate of the population proportion is .25. How large a sample is required?

A silkscreen printing company purchases t-shirts. To ensure the quality of the shipment, 300 t-shirts are randomly selected. Fifteen are defective. What is the estimated proportion defective in the population?

We want to estimate the population mean of waiting time in a doctor's office within 20 minutes, with a 99% level of confidence. The population standard deviation is estimated to be 15. How large a sample is required?

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. What is the 95% confidence interval for the population proportion?

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.

A population has a standard deviation of 25. We want to estimate the population mean within 2, with a 95% level of confidence. How large a sample is required?

A local health care company wants to estimate the mean weekly elder day-care cost. A sample of 10 facilities shows a mean of $250 per week, with a standard deviation of $25. What is the 90% confidence interval for the population mean?

A finite population correction factor is used when we know the _________________.