Question 1

When testing for the difference between two population variances with sample sizes of n1 = 8 and n2 = 10, the number of degrees of freedom are

Accepted Answer

A)  7 and 9. 
B)  18. 
C)  16. 
D)  8 and 10. 
A)  7 and 9. 
B)  18. 
C)  16. 
D)  8 and 10.

Question 2

TABLE 10-8
A buyer for a manufacturing plant suspects that his primary supplier of raw materials is overcharging. In order to determine if his suspicion is correct, he contacts a second supplier and asks for the prices on various identical materials. He wants to compare these prices with those of his primary supplier. The data collected is presented in the table below, with some summary statistics presented (all of these might not be necessary to answer the questions which follow). The buyer believes that the differences are normally distributed and will use this sample to perform an appropriate test at a level of significance of 0.01

$ \begin{array}{lll} & \text { Primary } & \text { Secondary } \ \text { Material } & \underline{\text { Supplier }} &\underline{\text { Supplier } }&\underline{\text { Difference }}\
1 & \$ 55 & \$ 45 & \$ 10 \ 2 & \$ 48 & \$ 47 & \$ 1 \ 3 & \$ 31 & \$ 32 & -\$ 1 \ 4 & \$ 83 & \$ 77 & \$ 6 \ 5 & \$ 37 & \$ 37 & \$ 0 \ 6 & \$ 55 & \$ 54 & \$ 1\
\hline \text { Sum: } & \$ 309 & \$ 292 & \$ 17 \ \text { Sum of Squares: } &\$ 17,573 & \$ 15,472 & \$ 139
\end{array} $

-Referring to Table 10-8, the hypotheses that the buyer should test are a null hypothesis that_____versus an alternative hypothesis that_____ .

Accepted Answer

The answer of TABLE 10-8
A buyer for a manufacturing plant...

Question 3

TABLE 10-2
A researcher randomly sampled 30 graduates of an MBA program and recorded data concerning their starting salaries. Of primary interest to the researcher was the effect of gender on starting salaries. Analysis of the mean salaries of the females and males in the sample is given below.
 
-Referring to Table 10-2, what is the 90% confidence interval estimate for the difference between two means?

Accepted Answer

- $14,903.

Question 4

TABLE 10-10
The following EXCEL output contains the results of a test to determine if the proportions of satisfied guests at two resorts are the same or different.
  
-Referring to Table 10-10, construct a 99% confidence interval estimate of the difference in the population proportion of satisfied guests between the two resorts.

Accepted Answer

The answer of TABLE 10-10
The following EXCEL output contains the...

Question 5

In testing for the differences between the means of two independent populations, we assume that the two populations each follow a(n)____ distribution.

Accepted Answer

The answer of In testing for the differences between the...

Question 6

TABLE 10-10 
 The following EXCEL output contains the results of a test to determine if the proportions of satisfied guests at two resorts are the same or different.
  
-Referring to Table 10-10, construct a 95% confidence interval estimate of the difference in the population proportion of satisfied guests between the two resorts.

Accepted Answer

The answer of TABLE 10-10 
 The following EXCEL output...

Question 7

$$\text { TABLE 10-10 }$$ The following EXCEL output contains the results of a test to determine if the proportions of satisfied guests at two resorts are the same or different.
  
-Referring to Table 10-10, allowing for 0.75% probability of committing a Type I error, what are the decision and conclusion on testing whether there is any difference in the proportions of satisfied guests in the two resorts?

Accepted Answer

A)  Reject the null hypothesis; there is enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts. 
B)  Do not reject the null hypothesis; there is enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts. 
C)  Reject the null hypothesis; there is not enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts. 
D)  Do not reject the null hypothesis; there is not enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts. 
A)  Reject the null hypothesis; there is enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts. 
B)  Do not reject the null hypothesis; there is enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts. 
C)  Reject the null hypothesis; there is not enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts. 
D)  Do not reject the null hypothesis; there is not enough evidence to conclude that there is significant difference in the proportions of satisfied guests at the two resorts.

Question 8

$$\text { TABLE 10-4 }$$ A real estate company is interested in testing whether, on average, families in Gotham have been living in their current homes for less time than families in Metropolis have. Assume that the two population variances are equal. A random sample of 100 families from Gotham and a random sample of 150 families in Metropolis yield the following data on length of residence in current homes.
 $$\text { Gotham: } X _ { G } = 35 \text { months, } s _G ^ { 2 } = 900 \text { Metropolis: } X _ { M } = 50 \text { months, } s^ 2_ { M }  = 1050$$ 
-Referring to Table 10-4, suppose ? = 0.01. Which of the following represents the result of the relevant hypothesis test?

Accepted Answer

A)  The alternative hypothesis is rejected. 
B)  The null hypothesis is not rejected. 
C)  The null hypothesis is rejected. 
D)  Insufficient information exists on which to make a decision. 
A)  The alternative hypothesis is rejected. 
B)  The null hypothesis is not rejected. 
C)  The null hypothesis is rejected. 
D)  Insufficient information exists on which to make a decision.

Question 9

A Marine drill instructor recorded the time in which each of 11 recruits completed an obstacle course both before and after basic training. To test whether any improvement occurred, the instructor would use a t-distribution with 10 degrees of freedom.

Accepted Answer

A) True 
 B)False

Question 10

A powerful women's group has claimed that men and women differ in attitudes about sexual discrimination. A group of 50 men (group 1) and 40 women (group 2) were asked if they thought sexual discrimination is a problem in the United States. Of those sampled, 11 of the men and 19 of the women did believe that sexual discrimination is a problem. Construct a 99% confidence interval estimate of the difference between the proportion of men and women who believe that sexual discrimination is a problem.

Accepted Answer

- 0.508 to

Question 11

TABLE 10-6
Two samples each of size 25 are taken from independent populations assumed to be normally distributed with equal variances. The first sample has a mean of 35.5 and standard deviation of 3.0 while the second sample has a mean of 33.0 and standard deviation of 4.0.
-Referring to Table 10-6, if we were interested in testing against the one-tailed alternative that µ1 > µ2 at the ? = 0.01 level of significance, the null hypothesis would ______.

Accepted Answer

Question 12

TABLE 10-14
A problem with a telephone line that prevents a customer from receiving or making calls is disconcerting to both the customer and the telephone company. The data on samples of 20 problems reported to two different offices of a telephone company and the time to clear these problems (in minutes) from the customers' lines are collected. Below is the Excel output to see whether there is evidence of a difference in the mean waiting time between the two offices assuming that the
population variances in the two offices are not equal.
 $$\text { t-Test: Two- Sample Assuming Unequal Variances }$$ 
$$\begin{array} { l r r } 
& \text { Office 1 } & \text { Office 2 } \
\hline \text { Mean } & 2214 & 2.0115 \
\text { Variance } & 2.951657 & 3.57855 \
\text { Observations } & 20 & 20 \
\text { Hypothesized Mean Difference } & 0 & \
\mathrm { df } & 38 & \
\mathrm { t } \text { Stat } & 0.354386 & \
\mathrm { P } ( \mathrm { T } < = \mathrm { t } ) \text { one- tail } & 0.362504 & \
\mathrm { t } \text { Critical one- tail } & 1.685953 & \
\mathrm { P } ( \mathrm { T } < = \mathrm { t } ) \text { two- tail } & 0.725009 & \
\mathrm { t } \text { Critical two-tail } & 2.024394 & \
\hline
\end{array}$$

-Referring to Table 10-13, construct a 95% confidence interval estimate of the difference in proportion between the Kohler and Russell disks that are defective.

Accepted Answer

The answer of TABLE 10-14
A problem with a telephone line...

Question 13

The F test used for testing the difference in two population variances is always a one-tailed test.

Accepted Answer

A) True 
 B)False

Question 14

TABLE 10-7
To investigate the efficacy of a diet, a random sample of 16 male patients is drawn from a population of adult males using the diet. The weight of each individual in the sample is taken at the start of the diet and at a medical follow-up 4 weeks later. Assuming that the population of differences in weight before versus after the diet follow a normal distribution, the t-test for related samples can be used to determine if there was a significant decrease in the mean weight during this period. Suppose the mean decrease in weights over all 16 subjects in the study is 3.0 pounds with the standard deviation of differences computed as 6.0 pounds.
-Referring to Table 10-7, what is the 95% confidence interval estimate for the mean difference in weight before and after the diet?

Accepted Answer

The answer of TABLE 10-7
To investigate the efficacy of a...

Question 15

When testing H0 : µ1 - µ2 ? 0 versus H1 : µ1 - µ2 > 0, the observed value of the Z-score was found to be - 2.13. The p-value for this test would be

Accepted Answer

A)  0.0166. 
B)  0.9834. 
C)  0.0332. 
D)  0.9668. 
A)  0.0166. 
B)  0.9834. 
C)  0.0332. 
D)  0.9668.

Question 16

TABLE 10-2
A researcher randomly sampled 30 graduates of an MBA program and recorded data concerning their starting salaries. Of primary interest to the researcher was the effect of gender on starting salaries. Analysis of the mean salaries of the females and males in the sample is given below.

-Referring to Table 10-2, the researcher was attempting to show statistically that the female MBA graduates have a significantly lower mean starting salary than the male MBA graduates. According to the test run, which of the following is an appropriate alternative hypothesis?

Accepted Answer

A) $ H_{1}: \mu_{\text {females }}=\mu_{\text {males }} $ B) $ H_{1}: \mu_{\text {females }} \neq \mu_{\text {males }} $ C) $ H_{1}: \mu_{\text {females }}>\mu_{\text {males }} $ D) $ H_{1}: \mu_{\text {females }}<\mu_{\text {males }} $ A) $ H_{1}: \mu_{\text {females }}=\mu_{\text {males }} $ B) $ H_{1}: \mu_{\text {females }} \neq \mu_{\text {males }} $ C) $ H_{1}: \mu_{\text {females }}>\mu_{\text {males }} $ D) $ H_{1}: \mu_{\text {females }}<\mu_{\text {males }} $

Question 17

TABLE 10-7
To investigate the efficacy of a diet, a random sample of 16 male patients is drawn from a population of adult males using the diet. The weight of each individual in the sample is taken at the start of the diet and at a medical follow-up 4 weeks later. Assuming that the population of differences in weight before versus after the diet follow a normal distribution, the t-test for related samples can be used to determine if there was a significant decrease in the mean weight during this period. Suppose the mean decrease in weights over all 16 subjects in the study is 3.0 pounds with the standard deviation of differences computed as 6.0 pounds.
-Referring to Table 10-7, what is the 99% confidence interval estimate for the mean difference in weight before and after the diet?

Accepted Answer

The answer of TABLE 10-7
To investigate the efficacy of a...

Question 18

TABLE 10-7
To investigate the efficacy of a diet, a random sample of 16 male patients is drawn from a population of adult males using the diet. The weight of each individual in the sample is taken at the start of the diet and at a medical follow-up 4 weeks later. Assuming that the population of differences in weight before versus after the diet follow a normal distribution, the t-test for related samples can be used to determine if there was a significant decrease in the mean weight during this period. Suppose the mean decrease in weights over all 16 subjects in the study is 3.0 pounds with the standard deviation of differences computed as 6.0 pounds.
-Referring to Table 10-7, if we were interested in testing against the two-tailed alternative that µD is not equal to zero at the ? = 0.05 level of significance, the null hypothesis would_________(be rejected/not be rejected).

Accepted Answer

The answer of TABLE 10-7
To investigate the efficacy of a...

Question 19

TABLE 10-3
The use of preservatives by food processors has become a controversial issue. Suppose 2 preservatives are extensively tested and determined safe for use in meats. A processor wants to compare the preservatives for their effects on retarding spoilage. Suppose 15 cuts of fresh meat are treated with preservative I and 15 are treated with preservative II, and the number of hours until spoilage begins is recorded for each of the 30 cuts of meat. The results are summarized in the table below.
 $$\begin{array} { l l } 
 \text {Preservative $A$}& \text { Preservative $B$}\
X _ { I } = 106.4 \text { hours } & X _ { \text {II } } = 96.54 \text { hours } \
S _ { I } = 10.3 \text { hours } & S _ { \text {II } } = 13.4 \text { hours }
\end{array}$$

-Referring to Table 10-3, what is the largest level of significance at which a test if the population variances differ for preservatives I and II will not be rejected?

Accepted Answer

0.3362 or 'greater t

Question 20

The sample size in each independent sample must be the same if we are to test for differences between the means of 2 independent populations.

Accepted Answer

A) True 
 B)False

When testing for the difference between two population variances with sample sizes of n₁ = 8 and n₂= 10, the number of degrees of freedom are

In testing for the differences between the means of two independent populations, we assume that the two populations each follow a(n)____ distribution.

A Marine drill instructor recorded the time in which each of 11 recruits completed an obstacle course both before and after basic training. To test whether any improvement occurred, the instructor would use a t-distribution with 10 degrees of freedom.

The F test used for testing the difference in two population variances is always a one-tailed test.

When testing H₀ : µ₁ - µ₂ ? 0 versus H₁ : µ₁ - µ₂ > 0, the observed value of the Z-score was found to be - 2.13. The p-value for this test would be

The sample size in each independent sample must be the same if we are to test for differences between the means of 2 independent populations.

Introduction and Data Collection

Presenting Data in Tables and Charts

Numerical Descriptive Measures

Basic Probability

Some Important Discrete Probability Distributions

The Normal Distribution and Other Continuous Distributions

Sampling Distributions and Sampling

Confidence Interval Estimation

Fundamentals of Hypothesis Testing: One-Sample Tests

Analysis of Variance

Chi-Square Tests and Nonparametric Tests

Simple Linear Regression

Introduction to Multiple Regression

Multiple Regression Model Building

Time-Series Forecasting and Index Numbers

Decision Making

Statistical Applications in Quality Management

Statistical Analysis Scenarios and Distributions

Filters

Exam 10: Two-Sample Tests

When testing for the difference between two population variances with sample sizes of n1 = 8 and n2 = 10, the number of degrees of freedom are

In testing for the differences between the means of two independent populations, we assume that the two populations each follow a(n)____ distribution.

A Marine drill instructor recorded the time in which each of 11 recruits completed an obstacle course both before and after basic training. To test whether any improvement occurred, the instructor would use a t-distribution with 10 degrees of freedom.

The F test used for testing the difference in two population variances is always a one-tailed test.

When testing H0 : µ1 - µ2 ? 0 versus H1 : µ1 - µ2 > 0, the observed value of the Z-score was found to be - 2.13. The p-value for this test would be

The sample size in each independent sample must be the same if we are to test for differences between the means of 2 independent populations.

Introduction and Data Collection

Presenting Data in Tables and Charts

Numerical Descriptive Measures

Basic Probability

Some Important Discrete Probability Distributions

The Normal Distribution and Other Continuous Distributions

Sampling Distributions and Sampling

Confidence Interval Estimation

Fundamentals of Hypothesis Testing: One-Sample Tests

Analysis of Variance

Chi-Square Tests and Nonparametric Tests

Simple Linear Regression

Introduction to Multiple Regression

Multiple Regression Model Building

Time-Series Forecasting and Index Numbers

Decision Making

Statistical Applications in Quality Management

Statistical Analysis Scenarios and Distributions

Filters

When testing for the difference between two population variances with sample sizes of n₁ = 8 and n₂= 10, the number of degrees of freedom are

When testing H₀ : µ₁ - µ₂ ? 0 versus H₁ : µ₁ - µ₂ > 0, the observed value of the Z-score was found to be - 2.13. The p-value for this test would be