Question 1

If the population variances are exactly equal,the sample F test statistic will be zero.

Accepted Answer

A) True 
 B)False  False

Question 2

Litter sizes (number of pups)for randomly chosen dogs from two breeds were compared.The sample data were entered into Excel,and the following results were produced. What is the p-value for a left-tailed test comparing the means at F1F1F1S1F1F1F10 = .05?

Accepted Answer

A)  Less than .10 
B)  More than .10 
C)  Between .10 and .05 
D)  Between .05 and .01 
A)  Less than .10 
B)  More than .10 
C)  Between .10 and .05 
D)  Between .05 and .01 B

Question 3

Group 1 has a mean of 13.4 and group 2 has a mean of 15.2.Both populations are known to have a variance of 9.0 and each sample consists of 18 items.What is the test statistic to test for equality of population means?

Accepted Answer

A)  -1.755 
B)  -1.643 
C)  -1.800 
D)  -1.285 
A)  -1.755 
B)  -1.643 
C)  -1.800 
D)  -1.285 C

Question 4

A random sample of Ersatz University students revealed that 16 females had a mean of $22.30 in their wallets with a standard deviation of $3.20,while 6 males had a mean of $17.30 with a standard deviation of $9.60.At F1F1F1S1F1F1F10 = .10,to test for equal variances in a two-tailed test,the critical values are:

Accepted Answer

A)  0.441 and 3.24 
B)  0.556 and 2.27 
C)  0.345 and 4.62 
D)  0.387 and 2.90 
A)  0.441 and 3.24 
B)  0.556 and 2.27 
C)  0.345 and 4.62 
D)  0.387 and 2.90

Question 5

The test statistic in an F test for equal variances is the ratio of the sample variances.

Accepted Answer

A) True 
 B)False

Question 6

The table below shows the mean number of daily errors by seven air traffic controller trainees during the first two weeks on the job.We want to perform a paired t-test at F1F1F1S1F1F1F10 = .05 to see if the mean daily errors have decreased from Week 1 to Week 2. The right-tailed critical value at F1F1F1S1F1F1F10 = 0.05 is:

Accepted Answer

A)  1.895 
B)  1.943 
C)  2.447 
D)  2.365 
A)  1.895 
B)  1.943 
C)  2.447 
D)  2.365

Question 7

In a random sample of patient records in Cutter Memorial Hospital,six-month postoperative exams were given in 90 out of 200 prostatectomy patients,while in Paymor Hospital such exams were given in 110 out of 200 cases.In comparing these two proportions,normality of the difference may be assumed because:

Accepted Answer

A)  the populations are large enough to be assumed normal. 
B)  the probability of success can reasonably be assumed constant. 
C)  the samples are random,so the proportions are unbiased estimates. 
D)  nF1F1F1S1F1F1F10 F1F1F1S1F1F1F10 10 and n(1 - F1F1F1S1F1F1F10)F1F1F1S1F1F1F10 10 for each sample taken separately. 
A)  the populations are large enough to be assumed normal. 
B)  the probability of success can reasonably be assumed constant. 
C)  the samples are random,so the proportions are unbiased estimates. 
D)  nF1F1F1S1F1F1F10 F1F1F1S1F1F1F10 10 and n(1 - F1F1F1S1F1F1F10)F1F1F1S1F1F1F10 10 for each sample taken separately.

Question 8

The table below shows the mean number of daily errors by air traffic controller trainees during the first two weeks on the job.We want to perform a paired t-test at F1F1F1S1F1F1F10 = .05 to see if the mean daily errors decreased significantly. The test statistic is:

Accepted Answer

A)  1.25 
B)  1.75 
C)  0.87 
D)  0.79 
A)  1.25 
B)  1.75 
C)  0.87 
D)  0.79

Question 9

Jason wants to perform a two-tailed test for equality between two independent sample proportions.Each sample has at least 10 "successes" and 10 "failures." Jason's test statistic is -1.44.What is his p-value?

Accepted Answer

A)  .1498 
B)  .0749 
C)  .9251 
D)  Between .01 and .05 
A)  .1498 
B)  .0749 
C)  .9251 
D)  Between .01 and .05

Question 10

The coach of an adult Master's Swim class selected eight swimmers within each of the two age groups shown below.A 50-yard freestyle time is recorded for each swimmer.The resulting times (seconds)are shown below.Which statistical test would you choose to compare the two groups?

Accepted Answer

A)  t-test for independent samples with known variances 
B)  t-test for independent samples with unknown variances 
C)  t-test for paired samples 
D)  z-test for two independent proportions 
A)  t-test for independent samples with known variances 
B)  t-test for independent samples with unknown variances 
C)  t-test for paired samples 
D)  z-test for two independent proportions

Question 11

A corporate analyst is testing whether mean inventory turnover has increased.Inventory turnover in six randomly chosen product distribution centers (PDCs)is shown. The right-tailed critical value at F1F1F1S1F1F1F10 = 0.005 is:

Accepted Answer

A)  1.645 
B)  1.479 
C)  4.032 
D)  2.015 
A)  1.645 
B)  1.479 
C)  4.032 
D)  2.015

Question 12

An F-test for equality of variances gives a p-value of .003.At F1F1F1S1F1F1F10 = .05,what conclusion can be made about the preferred test to compare the means for the same sample?

Accepted Answer

A)  We would prefer a pooled variance t-test for equality of means. 
B)  We would not wish to pool the variances in a t-test for equality of means. 
C)  We would prefer a paired t-test for equality of means. 
D)  The variances have nothing to do with the t-test for equality of means. 
A)  We would prefer a pooled variance t-test for equality of means. 
B)  We would not wish to pool the variances in a t-test for equality of means. 
C)  We would prefer a paired t-test for equality of means. 
D)  The variances have nothing to do with the t-test for equality of means.

Question 13

In a left-tailed test comparing two means with unknown variances assumed to be equal,the test statistic was t = -1.81 with sample sizes of n1 = 8 and n2 = 12.The p-value would be:

Accepted Answer

A)  between .025 and .05. 
B)  between .01 and .025. 
C)  between .05 and .10. 
D)  Must know F1F1F1S1F1F1F10 to answer. 
A)  between .025 and .05. 
B)  between .01 and .025. 
C)  between .05 and .10. 
D)  Must know F1F1F1S1F1F1F10 to answer.

Question 14

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.She weighed a random sample of five babies of each gender.Their weights (pounds)are shown below,along with some MegaStat results. The population means:

Accepted Answer

A)  may be assumed equal at any customary F1F1F1S1F1F1F10. 
B)  should be assumed unequal at any customary F1F1F1S1F1F1F10. 
C)  are not relevant to this paired t-test. 
A)  may be assumed equal at any customary F1F1F1S1F1F1F10. 
B)  should be assumed unequal at any customary F1F1F1S1F1F1F10. 
C)  are not relevant to this paired t-test.

Question 15

The table below shows two samples taken to compare the mean age of individuals who purchased the iPhone 3G at two AT&T store locations. What are the critical values for a two-tailed test for equal variances at F1F1F1S1F1F1F10 = .05?

Accepted Answer

A)  0.275,3.14 
B)  0.244,3.37 
C)  0.210,3.95 
D)  0.181,4.32 
A)  0.275,3.14 
B)  0.244,3.37 
C)  0.210,3.95 
D)  0.181,4.32

Question 16

The table below compares two samples taken to compare the mean age of individuals who purchased the iPhone 3G at two AT&T store locations.Very briefly,what conclusions can you draw?

Accepted Answer

In either test,the large test statistic

Question 17

A new policy of "flex hours" is proposed.Random sampling showed that 28 of 50 female workers favored the change,while 22 of 50 male workers favored the change.Management wonders if there is a difference between the two groups.What is the p-value for a two-tailed test?

Accepted Answer

A)  .3849 
B)  .1151 
C)  .2301 
D)  .3453 
A)  .3849 
B)  .1151 
C)  .2301 
D)  .3453

Question 18

Carver Memorial Hospital's surgeons have a new procedure that they think will decrease the time to perform an appendectomy.A sample of 8 appendectomies using the old method had a mean of 38 minutes with a variance of 36 minutes,while a sample of 10 appendectomies using the experimental method had a mean of 29 minutes with a variance of 16 minutes.For a right-tail test of equal means (assume equal variances),the pooled variance is:

Accepted Answer

A)  14.76 
B)  26.00 
C)  24.75 
D)  27.54 
A)  14.76 
B)  26.00 
C)  24.75 
D)  27.54

Question 19

The difference between two sample proportions p1 - p2 may be assumed normally distributed if each sample has at least 10 "successes" and 10 "failures."

Accepted Answer

A) True 
 B)False

Question 20

A paired t-test with two columns of 10 observations in each column would use d.f.= 18.

Accepted Answer

A) True 
 B)False

If the population variances are exactly equal,the sample F test statistic will be zero.

Litter sizes (number of pups)for randomly chosen dogs from two breeds were compared.The sample data were entered into Excel,and the following results were produced. What is the p-value for a left-tailed test comparing the means at  = .05?

Group 1 has a mean of 13.4 and group 2 has a mean of 15.2.Both populations are known to have a variance of 9.0 and each sample consists of 18 items.What is the test statistic to test for equality of population means?

A random sample of Ersatz University students revealed that 16 females had a mean of $22.30 in their wallets with a standard deviation of $3.20,while 6 males had a mean of $17.30 with a standard deviation of $9.60.At  = .10,to test for equal variances in a two-tailed test,the critical values are:

The test statistic in an F test for equal variances is the ratio of the sample variances.

The table below shows the mean number of daily errors by seven air traffic controller trainees during the first two weeks on the job.We want to perform a paired t-test at  = .05 to see if the mean daily errors have decreased from Week 1 to Week 2. The right-tailed critical value at  = 0.05 is:

The table below shows the mean number of daily errors by air traffic controller trainees during the first two weeks on the job.We want to perform a paired t-test at  = .05 to see if the mean daily errors decreased significantly. The test statistic is:

Jason wants to perform a two-tailed test for equality between two independent sample proportions.Each sample has at least 10 "successes" and 10 "failures." Jason's test statistic is -1.44.What is his p-value?

The coach of an adult Master's Swim class selected eight swimmers within each of the two age groups shown below.A 50-yard freestyle time is recorded for each swimmer.The resulting times (seconds)are shown below.Which statistical test would you choose to compare the two groups?

A corporate analyst is testing whether mean inventory turnover has increased.Inventory turnover in six randomly chosen product distribution centers (PDCs)is shown. The right-tailed critical value at  = 0.005 is:

An F-test for equality of variances gives a p-value of .003.At  = .05,what conclusion can be made about the preferred test to compare the means for the same sample?

In a left-tailed test comparing two means with unknown variances assumed to be equal,the test statistic was t = -1.81 with sample sizes of n₁ = 8 and n₂ = 12.The p-value would be:

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.She weighed a random sample of five babies of each gender.Their weights (pounds)are shown below,along with some MegaStat results. The population means:

The table below shows two samples taken to compare the mean age of individuals who purchased the iPhone 3G at two AT&T store locations. What are the critical values for a two-tailed test for equal variances at  = .05?

The table below compares two samples taken to compare the mean age of individuals who purchased the iPhone 3G at two AT&T store locations.Very briefly,what conclusions can you draw?

A new policy of "flex hours" is proposed.Random sampling showed that 28 of 50 female workers favored the change,while 22 of 50 male workers favored the change.Management wonders if there is a difference between the two groups.What is the p-value for a two-tailed test?

The difference between two sample proportions p₁ - p₂ may be assumed normally distributed if each sample has at least 10 "successes" and 10 "failures."

A paired t-test with two columns of 10 observations in each column would use d.f.= 18.

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Time-Series Analysis

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters

Exam 10: Two-Sample Hypothesis Tests

If the population variances are exactly equal,the sample F test statistic will be zero.

Litter sizes (number of pups)for randomly chosen dogs from two breeds were compared.The sample data were entered into Excel,and the following results were produced. What is the p-value for a left-tailed test comparing the means at  = .05?

Group 1 has a mean of 13.4 and group 2 has a mean of 15.2.Both populations are known to have a variance of 9.0 and each sample consists of 18 items.What is the test statistic to test for equality of population means?

The test statistic in an F test for equal variances is the ratio of the sample variances.

The table below shows the mean number of daily errors by air traffic controller trainees during the first two weeks on the job.We want to perform a paired t-test at  = .05 to see if the mean daily errors decreased significantly. The test statistic is:

Jason wants to perform a two-tailed test for equality between two independent sample proportions.Each sample has at least 10 "successes" and 10 "failures." Jason's test statistic is -1.44.What is his p-value?

The coach of an adult Master's Swim class selected eight swimmers within each of the two age groups shown below.A 50-yard freestyle time is recorded for each swimmer.The resulting times (seconds)are shown below.Which statistical test would you choose to compare the two groups?

A corporate analyst is testing whether mean inventory turnover has increased.Inventory turnover in six randomly chosen product distribution centers (PDCs)is shown. The right-tailed critical value at  = 0.005 is:

An F-test for equality of variances gives a p-value of .003.At  = .05,what conclusion can be made about the preferred test to compare the means for the same sample?

In a left-tailed test comparing two means with unknown variances assumed to be equal,the test statistic was t = -1.81 with sample sizes of n1 = 8 and n2 = 12.The p-value would be:

A medical researcher wondered if there is a significant difference between the mean birth weight of boy and girl babies.She weighed a random sample of five babies of each gender.Their weights (pounds)are shown below,along with some MegaStat results. The population means:

The table below shows two samples taken to compare the mean age of individuals who purchased the iPhone 3G at two AT&T store locations. What are the critical values for a two-tailed test for equal variances at  = .05?

The table below compares two samples taken to compare the mean age of individuals who purchased the iPhone 3G at two AT&T store locations.Very briefly,what conclusions can you draw?

A new policy of "flex hours" is proposed.Random sampling showed that 28 of 50 female workers favored the change,while 22 of 50 male workers favored the change.Management wonders if there is a difference between the two groups.What is the p-value for a two-tailed test?

The difference between two sample proportions p1 - p2 may be assumed normally distributed if each sample has at least 10 "successes" and 10 "failures."

A paired t-test with two columns of 10 observations in each column would use d.f.= 18.

Overview of Statistics

Data Collection

Describing Data Visually

Descriptive Statistics

Probability

Discrete Probability Distributions

Continuous Probability Distributions

Sampling Distributions and Estimation

One-Sample Hypothesis Tests

Analysis of Variance

Simple Regression

Multiple Regression

Time-Series Analysis

Chi-Square Tests

Nonparametric Tests

Quality Management

Filters

In a left-tailed test comparing two means with unknown variances assumed to be equal,the test statistic was t = -1.81 with sample sizes of n₁ = 8 and n₂ = 12.The p-value would be:

The difference between two sample proportions p₁ - p₂ may be assumed normally distributed if each sample has at least 10 "successes" and 10 "failures."