Question 1

The ____________________ confidence limit of the confidence interval estimator of the population variance is  .

Accepted Answer

The answer of The ____________________ confidence limit of the confidence...

Question 2

Mystic Pizza Mystic Pizza in Mystic, Connecticut, advertises that they deliver your pizza within 15 minutes of placing an order or it is free. A sample of 25 customers is selected at random. The average delivery time in the sample was 13 minutes with a sample standard deviation of 4 minutes. {Mystic Pizza Narrative} We want to know whether Mystic can make this claim or not. Test to determine if we can infer at the 5% significance level that the population mean delivery time is less than 15 minutes.

Accepted Answer

The answer of Mystic Pizza Mystic Pizza in Mystic, Connecticut,...

Question 3

The test statistic used to test hypotheses about the population variance has a chi-squared distribution with ____________________ degrees of freedom.

Accepted Answer

The answer of The test statistic used to test hypotheses...

Question 4

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population. The mean and standard deviation of the sample were $120 and $25, respectively. {Concert Tickets Narrative} Explain how to use the confidence interval to test the hypotheses at a = 0.10.

Accepted Answer

The answer of Concert Tickets A simple random sample of...

Question 5

The t- distribution assumes that the population is normally distributed.

Accepted Answer

A) True 
 B)False

Question 6

If a sample has 18 observations and a 90% confidence estimate for m is needed, the appropriate value of t is 1.740.

Accepted Answer

A) True 
 B)False

Question 7

For a 99% confidence interval of the population mean based on a sample of n = 25 with s = 0.05, the critical value of t is:

Accepted Answer

A) 2.7969 
B) 2.7874 
C) 2.4922 
D) 2.4851

Question 8

When the population standard deviation is unknown and the population is normal, the test statistic for testing hypotheses about m is the ____________________- distribution with ____________________ degrees of freedom.

Accepted Answer

The answer of When the population standard deviation is unknown...

Question 9

Which of the following conditions is needed regarding the chi-squared test statistic for the test of variance?

Accepted Answer

A) The population random variable must be normal. 
B) The test statistic must be a non-negative number. 
C) The test statistic must have a chi-squared distribution with n - 1 degrees of freedom. 
D) All of these choices are true.

Question 10

The sales manager of a large multinational corporation is concerned that some salespersons perform very well and others quite poorly. To help analyze the problem he draws a random sample of 20 salespersons, determines their commission incomes (in thousands of dollars), and calculates the following statistics: = $37.2, and s = $7.8. Do these statistics provide sufficient evidence at the 5% significance level to conclude that the population variance exceeds $35 million²?

Accepted Answer

The answer of The sales manager of a large multinational...

Question 11

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic. Their ages are 22, 17, 27, 20, 23, 19, 24, 18, 19, and 24 years. {Single Mothers' Ages Narrative} Test to determine if we can infer at the 5% significance level that the population mean is not equal to 20.

Accepted Answer

The answer of Single Mothers' Ages A random sample of...

Question 12

A life insurance representative believes that the mean age of people who buy their first life insurance plan is less than 35. To test his belief he takes a random sample of 15 customers who have just purchased their first life insurance. Their ages are 42, 43,28, 34, 30, 36, 25, 29, 32, 33, 27, 30, 22, 37, and 40. There is not enough evidence to say the data are nonnormal. Can we conclude at the 1% significance level that the insurance representative is correct?

Accepted Answer

The answer of A life insurance representative believes that the...

Question 13

During a natural gas shortage, a gas company randomly sampled residential gas meters in order to monitor daily gas consumption. On a particular day, a sample of 100 meters showed a sample mean of 250 cubic feet and a sample standard deviation of 50 cubic feet. Provide a 90% confidence interval estimate of the mean gas consumption for the population.

Accepted Answer

The answer of During a natural gas shortage, a gas...

Question 14

A robust estimator is one that is:

Accepted Answer

A) unbiased and symmetrical about zero. 
B) consistent and is also mound-shaped. 
C) efficient and less spread out. 
D) not sensitive to moderate nonnormality.

Question 15

The t -distribution is used to develop a confidence interval estimate of the population mean when the population standard deviation is unknown.

Accepted Answer

A) True 
 B)False

Question 16

The chi-squared test and estimator of the population variance ____________________(are\are not)valid if the population is slightly to moderately nonnormal.

Accepted Answer

The answer of The chi-squared test and estimator of the...

Question 17

An investor is concerned with the risk associated with a portfolio of stocks. He draws a random sample of nine monthly returns (expressed as a percentage of the initial investment). These data follow: 2, 5, - 6, 10, 1, 2, - 3, 0, and 7. Find a 95% confidence interval estimate of the population variance.

Accepted Answer

The answer of An investor is concerned with the risk...

Question 18

Hourly Fees A random sample of 15 hourly fees for car washers (including tips)was drawn from a normal population. The sample mean and sample standard deviation were  = $14.9 and s = $6.75. {Hourly Fees Narrative} Can we infer at the 5% significance level that the population mean is greater than 12, assuming that you know the population standard deviation is equal to 6.75?

Accepted Answer

The answer of Hourly Fees A random sample of 15...

Question 19

The ____________________ confidence limit of the confidence interval estimator of the population variance is  .

Accepted Answer

The answer of The ____________________ confidence limit of the confidence...

Question 20

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population. The mean and standard deviation of the sample were $120 and $25, respectively. {Concert Tickets Narrative} Estimate the population mean with 90% confidence.

Accepted Answer

The answer of Concert Tickets A simple random sample of...

Exam 11: Inference About a Population

The ____________________ confidence limit of the confidence interval estimator of the population variance is .

The test statistic used to test hypotheses about the population variance has a chi-squared distribution with ____________________ degrees of freedom.

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population. The mean and standard deviation of the sample were $120 and $25, respectively. {Concert Tickets Narrative} Explain how to use the confidence interval to test the hypotheses at a = 0.10.

The t- distribution assumes that the population is normally distributed.

If a sample has 18 observations and a 90% confidence estimate for m is needed, the appropriate value of t is 1.740.

For a 99% confidence interval of the population mean based on a sample of n = 25 with s = 0.05, the critical value of t is:

When the population standard deviation is unknown and the population is normal, the test statistic for testing hypotheses about m is the - distribution with degrees of freedom.

Which of the following conditions is needed regarding the chi-squared test statistic for the test of variance?

Single Mothers' Ages A random sample of 10 single mothers was drawn from a Obstetrics Clinic. Their ages are 22, 17, 27, 20, 23, 19, 24, 18, 19, and 24 years. {Single Mothers' Ages Narrative} Test to determine if we can infer at the 5% significance level that the population mean is not equal to 20.

A robust estimator is one that is:

The t -distribution is used to develop a confidence interval estimate of the population mean when the population standard deviation is unknown.

The chi-squared test and estimator of the population variance ____________________(are\are not)valid if the population is slightly to moderately nonnormal.

The ____________________ confidence limit of the confidence interval estimator of the population variance is .

Concert Tickets A simple random sample of 100 concert tickets was drawn from a normal population. The mean and standard deviation of the sample were $120 and $25, respectively. {Concert Tickets Narrative} Estimate the population mean with 90% confidence.