Question 1

When two independent random samples of sizes   and   have been selected from populations with means   and   , and variances   and   , which of the following is true?

Accepted Answer

A)  The mean ofis. 
B)  The standard error ofis. 
C)  The standard error ofis estimated as. 
D)  All of these. 
E)  None of these. 
A)  The mean ofis. 
B)  The standard error ofis. 
C)  The standard error ofis estimated as. 
D)  All of these. 
E)  None of these.

Question 2

When two independent random samples of sizes   and   have been selected from populations with means   and   and variances   and   , the standard error of the sampling distribution of   the difference between the two sample means, is found by taking the square root of the sum of the two population variances; namely,   .

Accepted Answer

A) True 
 B)False

Question 3

If you wish to estimate the difference between two population means when the population variances are known, the 90% confidence interval estimate can be developed using which of the following critical values of z?

Accepted Answer

A)  2.33 
B)  1.28 
C)  1.96 
D)  2.58 
E)  1.645 
A)  2.33 
B)  1.28 
C)  1.96 
D)  2.58 
E)  1.645

Question 4

Two samples are said to be independent if they are selected at different points in time.

Accepted Answer

A) True 
 B)False

Question 5

The sample standard deviation s is an unbiased estimator of the population standard deviation   .

Accepted Answer

A) True 
 B)False

Question 6

A state job service employee wishes to estimate the mean number of people who register with the service each week. How many weeks should be sampled in order to estimate the mean number of weekly registrants? The employee would like the margin of error to be less than 0.5 with probability of 0.95. Past records show the weekly standard deviation to be 2.5.
______________ weeks

Accepted Answer

The answer of A state job service employee wishes to...

Question 7

A random sample of n = 1000 observations from a binomial population produced x = 728 successes.
Estimate the binomial proportion p.
______________
Calculate the margin of error.
______________

Accepted Answer

The answer of A random sample of n = 1000...

Question 8

Independent samples of n1 = 400 and n2 = 400 observations were selected from binomial populations 1 and 2, and x1 = 100 and x2 = 127 successes were observed.
a. What is the best point estimator for the difference (p1 - p2) in the two binomial proportions?
______________
b. Calculate the approximate standard error for the statistic used in part (a).
______________
c. What is the margin of error for this point estimate?
______________

Accepted Answer

-0.0675; 0

Question 9

Suppose a 95% confidence interval for the mean height of a 12-year-old male in the United States is 54 to 65 inches. It can be said that 95% of 12-year-old males in the U.S. have height greater than or equal to 54 inches and less than or equal to 65 inches.

Accepted Answer

A) True 
 B)False

Question 10

In order to estimate the average numbers of miles that students who live off-campus commute to classes every day, the following statistics were given: n = 50,   = 5.21, and s = 2.48. The point estimate of the true population mean   is:

Accepted Answer

A)  1.96 
B)  2.10 
C)  5.21 
D)  7.07 
E)  2.78 
A)  1.96 
B)  2.10 
C)  5.21 
D)  7.07 
E)  2.78

Question 11

The manufacturer of a particular battery pack for a laptop computer claims the battery pack can function for 8 hours, on the average, before having to be recharged. A random sample of 36 such battery packs was selected and tested. The mean and standard deviation were found to be 6 hours and 1.8 hours, respectively.
Find a 90% confidence interval for the true average time the battery pack can function before having to be recharged.
______________
Based on the interval above, can the manufacturer's claim be rejected?
______________
Explain.
________________________________________________________

Accepted Answer

(5.5065, 6.4935); Yes; Since 8

Question 12

In order to construct a confidence interval estimate of the population proportion p, the value of p is needed.

Accepted Answer

A) True 
 B)False

Question 13

It is desired to compare the average ages at which men and women get their first license to drive. A random sample of 75 men yielded a mean and standard deviation of 17.3 and 4.7 years, respectively. A random sample of 96 women yielded a mean and standard deviation of 19.6 and 5.1 years, respectively. If it is desired to estimate the mean difference to within 1.5 years with 95% confidence, how large a sample should be taken from each population? Assume n1 = n2 = n.
______________

Accepted Answer

Question 14

If a store manager has recently stated that she estimates the mean amount spent per customer per visit to be between $38.75 and $72.23, the numbers $38.75 and $72.23 are considered point estimates for the true population mean.

Accepted Answer

A) True 
 B)False

Question 15

The lower limit of a confidence interval at the 95% level of confidence for the population proportion if a sample of size 100 had 30 successes is:

Accepted Answer

A)  0.3898 
B)  0.2102 
C)  0.2959 
D)  0.3041 
E)  0.3126 
A)  0.3898 
B)  0.2102 
C)  0.2959 
D)  0.3041 
E)  0.3126

Question 16

The error of estimation is the difference between a statistic computed from a sample and the corresponding parameter computed from the population.

Accepted Answer

A) True 
 B)False

Question 17

In a study of radio listening habits, a station owner would like to estimate the average number of hours that teenagers spend listening each day. If it is reasonable to assume that   = 1.3 hours, how large a sample size is needed to be 90% confident that the sample mean is off by at most 30 minutes?
______________

Accepted Answer

The answer of In a study of radio listening habits,...

Question 18

From a sample of 200 items, 12 items are defective. The point estimate of the population proportion defective will be:

Accepted Answer

A)  12 
B)  0.06 
C)  16.67 
D)  0.12 
E)  1.6 
A)  12 
B)  0.06 
C)  16.67 
D)  0.12 
E)  1.6

Question 19

Two independent random samples of sizes   and   have been selected from binomial populations with parameters   and   , respectively, and resulted in 38 and 65 success, respectively. Then the standard error of   is estimated as .077.

Accepted Answer

A) True 
 B)False

Question 20

A college graduate school president is interested in knowing what proportion of applicants would like to be accepted into the chemistry department. Of a random sample of 75 applicants, 12 requested the chemistry department. Construct a 95% confidence interval for p, the true proportion of all applicants that prefer chemistry.
______________

Accepted Answer

The answer of A college graduate school president is interested...

When two independent random samples of sizes and have been selected from populations with means and , and variances and , which of the following is true?

If you wish to estimate the difference between two population means when the population variances are known, the 90% confidence interval estimate can be developed using which of the following critical values of z?

Two samples are said to be independent if they are selected at different points in time.

The sample standard deviation s is an unbiased estimator of the population standard deviation .

A random sample of n = 1000 observations from a binomial population produced x = 728 successes. Estimate the binomial proportion p. Calculate the margin of error.

Suppose a 95% confidence interval for the mean height of a 12-year-old male in the United States is 54 to 65 inches. It can be said that 95% of 12-year-old males in the U.S. have height greater than or equal to 54 inches and less than or equal to 65 inches.

In order to estimate the average numbers of miles that students who live off-campus commute to classes every day, the following statistics were given: n = 50, = 5.21, and s = 2.48. The point estimate of the true population mean is:

In order to construct a confidence interval estimate of the population proportion p, the value of p is needed.

If a store manager has recently stated that she estimates the mean amount spent per customer per visit to be between $38.75 and $72.23, the numbers $38.75 and $72.23 are considered point estimates for the true population mean.

The lower limit of a confidence interval at the 95% level of confidence for the population proportion if a sample of size 100 had 30 successes is:

The error of estimation is the difference between a statistic computed from a sample and the corresponding parameter computed from the population.

From a sample of 200 items, 12 items are defective. The point estimate of the population proportion defective will be:

Two independent random samples of sizes and have been selected from binomial populations with parameters and , respectively, and resulted in 38 and 65 success, respectively. Then the standard error of is estimated as .077.

Describing Data With Graphs

Describing Data With Numerical Measures

Describing Bivariate Data

Probability and Probability Distributions

Several Useful Discrete Distributions

The Normal Probability Distribution

Sampling Distributions

Large-Sample Tests of Hypotheses

Inference From Small Samples

The Analysis of Variance

Linear Regression and Correlation

Multiple Regression Analysis

Analysis of Categorical Data

Nonparametric Statistics

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Exam 8: Large-Sample Estimation

When two independent random samples of sizes and have been selected from populations with means and , and variances and , which of the following is true?

If you wish to estimate the difference between two population means when the population variances are known, the 90% confidence interval estimate can be developed using which of the following critical values of z?

Two samples are said to be independent if they are selected at different points in time.

The sample standard deviation s is an unbiased estimator of the population standard deviation .

A random sample of n = 1000 observations from a binomial population produced x = 728 successes. Estimate the binomial proportion p. ______________ Calculate the margin of error. ______________

Suppose a 95% confidence interval for the mean height of a 12-year-old male in the United States is 54 to 65 inches. It can be said that 95% of 12-year-old males in the U.S. have height greater than or equal to 54 inches and less than or equal to 65 inches.

In order to estimate the average numbers of miles that students who live off-campus commute to classes every day, the following statistics were given: n = 50, = 5.21, and s = 2.48. The point estimate of the true population mean is:

In order to construct a confidence interval estimate of the population proportion p, the value of p is needed.

If a store manager has recently stated that she estimates the mean amount spent per customer per visit to be between $38.75 and $72.23, the numbers $38.75 and $72.23 are considered point estimates for the true population mean.

The lower limit of a confidence interval at the 95% level of confidence for the population proportion if a sample of size 100 had 30 successes is:

The error of estimation is the difference between a statistic computed from a sample and the corresponding parameter computed from the population.

From a sample of 200 items, 12 items are defective. The point estimate of the population proportion defective will be:

Two independent random samples of sizes and have been selected from binomial populations with parameters and , respectively, and resulted in 38 and 65 success, respectively. Then the standard error of is estimated as .077.

Describing Data With Graphs

Describing Data With Numerical Measures

Describing Bivariate Data

Probability and Probability Distributions

Several Useful Discrete Distributions

The Normal Probability Distribution

Sampling Distributions

Large-Sample Tests of Hypotheses

Inference From Small Samples

The Analysis of Variance

Linear Regression and Correlation

Multiple Regression Analysis

Analysis of Categorical Data

Nonparametric Statistics

Filters

A random sample of n = 1000 observations from a binomial population produced x = 728 successes. Estimate the binomial proportion p. Calculate the margin of error.