Question 1

If you are testing for the difference between the means of two independent populations presuming equal variances with samples of n1 = 20 and n2 = 20,the number of degrees of freedom is equal to

Accepted Answer

A)  39. 
B)  19. 
C)  18. 
D)  38.

Question 2

Instruction 10-12
A corporation randomly selects 150 salespeople and finds that 66% who have never taken a self-improvement course would like such a course. The firm did a similar study 10 years ago in which 60% of a random sample of 160 salespeople wanted a self-improvement course. The groups are assumed to be independent random samples. Let πS1U1B11S1U1B0 and πS1U1B12S1U1B0 represent the true proportion of workers who would like to attend a self-improvement course in the recent study and the past study, respectively.
-Referring to Instruction 10-12,what is the value of the test statistic to use in evaluating the alternative hypothesis that there is a difference in the two population proportions?

Accepted Answer

A)  0 
B)  1.96 
C)  1.093 
D)  4.335

Question 3

Instruction 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 kilograms with the standard deviation of differences computed as 6.0 kilograms.
-Referring to Instruction 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 Instruction 10-7
To investigate the efficacy of a...

Question 4

Instruction 10-10
The dean of a college is interested in the proportion of graduates from his college who have a job offer on graduation day. He is particularly interested in seeing if there is a difference in this proportion for accounting and economics majors. In a random sample of 100 of each type of major at graduation, he found that 65 accounting students and 52 economics students had job offers. If the accounting students are designated as "Group 1" and the economics students are designated as "Group 2", perform the appropriate hypothesis test using a level of significance of 0.05.
-Referring to Instruction 10-13,the value of the test statistic is  _______.

Accepted Answer

The answer of Instruction 10-10
The dean of a college is...

Question 5

Instruction 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 Instruction 10-6,what is the 99% confidence interval estimate for the difference in the two means?

Accepted Answer

The answer of Instruction 10-6
Two samples each of size 25...

Question 6

Instruction 10-12
A corporation randomly selects 150 salespeople and finds that 66% who have never taken a self-improvement course would like such a course. The firm did a similar study 10 years ago in which 60% of a random sample of 160 salespeople wanted a self-improvement course. The groups are assumed to be independent random samples. Let πS1U1B11S1U1B0 and πS1U1B12S1U1B0 represent the true proportion of workers who would like to attend a self-improvement course in the recent study and the past study, respectively.
-Referring to Instruction 10-12,construct a 90% confidence interval estimate of the difference in proportion of workers who would like to attend a self-improvement course in the recent study and the past study.

Accepted Answer

The answer of Instruction 10-12
A corporation randomly selects 150 salespeople...

Question 7

In what type of test is the variable of interest the difference between the values of the observations rather than the observations themselves?

Accepted Answer

A)  A test for the difference between the means of two independent populations. 
B)  A test for the equality of variances from two independent populations. 
C)  A test for the difference between the means of two related populations. 
D)  All of the above.

Question 8

Instruction 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 Instruction 10-6,there are __________degrees of freedom for this test.

Accepted Answer

The answer of Instruction 10-6
Two samples each of size 25...

Question 9

Instruction 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 Instruction 10-6,what is the 90% confidence interval estimate for the difference in the two means?

Accepted Answer

The answer of Instruction 10-6
Two samples each of size 25...

Question 10

A business statistics lecturer wanted to test whether the grades on a business statistics test were the same for upper and lower students.The lecturer took a random sample of size 10 from each,conducted a test and found out that the variances were equal.For this situation,the lecturer should use a t test with independent samples.

Accepted Answer

A) True 
 B)False

Question 11

Instruction 10-14
A quality control engineer is in charge of the manufacture of computer disks. Two different processes can be used to manufacture the disks. He suspects that the Kohler method produces a greater proportion of defects than the Russell method. He samples 150 of the Kohler and 200 of the Russell disks and finds that 27 and 18 of them, respectively, are defective. If Kohler is designated as "Group 1" and Russell is designated as "Group 2", perform the appropriate test at a level of significance of 0.01.
-Referring to Instruction 10-14,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 Instruction 10-14
A quality control engineer is in...

Question 12

The statistical distribution used for testing the difference between two population variances is the __________ distribution.

Accepted Answer

A)  F 
B)  t 
C)  standardised normal 
D)  binomial

Question 13

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 Australia.Of those sampled,11 of the men and 19 of the women did believe that sexual discrimination is a problem.
- What is the value of the test statistic?

Accepted Answer

A)  Z = -1.20 
B)  Z = -1.05 
C)  Z = -0.85 
D)  Z = -2.55

Question 14

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

-Referring to Instruction 10-5,the calculated value of the test statistic is __________.

Accepted Answer

The answer of Instruction 10-5
A buyer for a manufacturing plant...

Question 15

Instruction 10-10
The dean of a college is interested in the proportion of graduates from his college who have a job offer on graduation day. He is particularly interested in seeing if there is a difference in this proportion for accounting and economics majors. In a random sample of 100 of each type of major at graduation, he found that 65 accounting students and 52 economics students had job offers. If the accounting students are designated as "Group 1" and the economics students are designated as "Group 2", perform the appropriate hypothesis test using a level of significance of 0.05.
-Referring to Instruction 10-13,construct a 95% confidence interval estimate of the difference in proportion between accounting majors and economic majors who have a job offer on graduation day.

Accepted Answer

The answer of Instruction 10-10
The dean of a college is...

Question 16

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

-Referring to Instruction 10-5,what is the 90% confidence interval estimate for the mean difference in prices?

Accepted Answer

The answer of Instruction 10-5
A buyer for a manufacturing plant...

Question 17

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)  16. 
C)  8 and 10. 
D)  18.

Question 18

Instruction 10-3
A real estate company is interested in testing whether the mean time that families in Gotham have been living in their current homes is less than families in Metropolis. 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.
Gotham: $\quad \bar { X } _ { G } = 35$ months, $S _ { G } { } ^ { 2 } = 900$
Metropolis: $\quad \bar { X } _ { M } = 50$ months, $\quad S _ { M ^ { 2 } } = 1,050$
-Referring to Instruction 10-3,what is a point estimate for the mean of the sampling distribution of the difference between the two sample means?

Accepted Answer

A)  -10 
B)  0 
C)  -22 
D)  -15

Question 19

Instruction 10-10
The dean of a college is interested in the proportion of graduates from his college who have a job offer on graduation day. He is particularly interested in seeing if there is a difference in this proportion for accounting and economics majors. In a random sample of 100 of each type of major at graduation, he found that 65 accounting students and 52 economics students had job offers. If the accounting students are designated as "Group 1" and the economics students are designated as "Group 2", perform the appropriate hypothesis test using a level of significance of 0.05.
-Referring to Instruction 10-13,the null hypothesis should be rejected.

Accepted Answer

A) True 
 B)False

Question 20

The test for the equality of two population variances assumes that each of the two populations is normally distributed.

Accepted Answer

A) True 
 B)False

Exam 10: Hypothesis Testing: Two-Sample Tests

If you are testing for the difference between the means of two independent populations presuming equal variances with samples of n₁ = 20 and n₂ = 20,the number of degrees of freedom is equal to

In what type of test is the variable of interest the difference between the values of the observations rather than the observations themselves?

The statistical distribution used for testing the difference between two population variances is the __________ distribution.

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

The test for the equality of two population variances assumes that each of the two populations is normally distributed.