Question 1

The following plot is the best for checking

Accepted Answer

A)  Equal Variance Assumption. 
B)  Linearity Assumption. 
C)  Nearly Normal Condition. 
D)  Non-linear Condition. 
E)  Dependence Condition. 
A)  Equal Variance Assumption. 
B)  Linearity Assumption. 
C)  Nearly Normal Condition. 
D)  Non-linear Condition. 
E)  Dependence Condition.

Question 2

Use the following to answer the question(s) below.
In economic downturns companies attempt to downsize their workforces by offering early retirement incentives to older employees. A survey of 723 companies found that 195 engage in such downsizing practices.
-The 99% confidence interval for the proportion of companies that downsize their workforces by offering early retirement incentives is

Accepted Answer

A)  0.19 to 0.35. 
B)  0.65 to 0.81. 
C)  0.19 to 0.47. 
D)  0.69 to 0.77. 
E)  0.23 to 0.31. 
A)  0.19 to 0.35. 
B)  0.65 to 0.81. 
C)  0.19 to 0.47. 
D)  0.69 to 0.77. 
E)  0.23 to 0.31.

Question 3

Which of the following is not an assumption or condition that needs to be checked for a two-sample t-test for the difference between two means?

Accepted Answer

A)  Independence Assumption 
B)  Randomization Condition 
C)  10% Condition 
D)  Nearly Normal Condition 
E)  90% Condition 
A)  Independence Assumption 
B)  Randomization Condition 
C)  10% Condition 
D)  Nearly Normal Condition 
E)  90% Condition

Question 4

Use the following to answer the question(s) below.
Insurance company records indicate that 10% of its policyholders file claims involving theft or robbery of personal property from their homes. Suppose a random sample of 400 policyholders is selected.
-The probability that the sample proportion of policyholders filing claims involving theft or robbery of personal property from their homes is less than 8% is

Accepted Answer

A)  0.0918. 
B)  0.1333. 
C)  0.4082. 
D)  0.0517. 
E)  0.7892. 
A)  0.0918. 
B)  0.1333. 
C)  0.4082. 
D)  0.0517. 
E)  0.7892.

Question 5

A type I error is committed when

Accepted Answer

A)  we don't reject a null hypothesis that is true. 
B)  we reject a null hypothesis that is false. 
C)  we reject a null hypothesis that is true. 
D)  we don't reject a null hypothesis that is false. 
E)  the null hypothesis is not properly constructed. 
A)  we don't reject a null hypothesis that is true. 
B)  we reject a null hypothesis that is false. 
C)  we reject a null hypothesis that is true. 
D)  we don't reject a null hypothesis that is false. 
E)  the null hypothesis is not properly constructed.

Question 6

Use the following to answer the question(s) below.
Three brands of AAA batteries are compared to determine if differences in lifetime exist. Each brand is tested in four devices (TV remote, hand-held game, flashlight and digital camera). The experiment is run once for each combination of brand and device. The twelve runs are ordered randomly. The time (in minutes) that each battery lasts under continuous usage is recorded. The partial ANOVA results are as follows:  
-The P-value associated with this F-statistic associated with the brands is 0.128. Based on this, we can conclude that

Accepted Answer

A)  we should reject the null hypothesis. 
B)  there is a difference in the mean lifetimes among the different brands. 
C)  there is no significant difference in the mean lifetimes among the different devices. 
D)  we should support the alternative hypothesis. 
E)  there is no difference in the mean lifetimes among the different brands. 
A)  we should reject the null hypothesis. 
B)  there is a difference in the mean lifetimes among the different brands. 
C)  there is no significant difference in the mean lifetimes among the different devices. 
D)  we should support the alternative hypothesis. 
E)  there is no difference in the mean lifetimes among the different brands.

Question 7

Use the following to answer the question(s) below.
A men's clothing store has determined the following probability distribution for the number of special size orders placed per month. The distribution is as follows:
Number Ordered Probability
0 0.10
5 0.10
10 0.12
15 0.30
20 0.38
-The number of special size orders this men's clothing store can expect per month is

Accepted Answer

A)  13.8. 
B)  20. 
C)  15. 
D)  14.2. 
E)  12.5. 
A)  13.8. 
B)  20. 
C)  15. 
D)  14.2. 
E)  12.5.

Question 8

Use the following to answer the question(s) below.
A local politician was interested in determining whether income level affects opinion regarding the governments' bailout bill of the auto industry during the 2008 financial crisis. He surveyed a sample of his constituents and got the following results.
Opinion
  
-At the 0.01 level of significance, the correct conclusion is

Accepted Answer

A) income level affects opinion. B) there is a relationship between income level and opinion. C) since P-value = 0.024 > 0.01, we fail to reject the null hypothesis. Opinion and income level are independent. D) reject the null hypothesis. E) as χ2 = 7.433 < χcr2 = 9.210, we support the alternative hypothesis and find that there is an association between income level and opinion. A) income level affects opinion. B) there is a relationship between income level and opinion. C) since P-value = 0.024 > 0.01, we fail to reject the null hypothesis. Opinion and income level are independent. D) reject the null hypothesis. E) as χ2 = 7.433 < χcr2 = 9.210, we support the alternative hypothesis and find that there is an association between income level and opinion.

Question 9

The best tasting ice creams are generally high in fat content, which gives them a creamy texture. Four brands of ice cream (two national and two local) were tested by consumers who graded their level of creaminess (A = very creamy to F = not creamy). Each brand was rated by a different group of consumers (the data are shown below).   Using the Kruskal-Wallis test, at α = 0.10 we would conclude that

Accepted Answer

A)  the alternative hypothesis should be rejected. 
B)  the null hypothesis should be accepted. 
C)  there is no difference in creaminess among the brands. 
D)  the null hypothesis should be rejected and at least one of the brands has a different distribution from the others. 
E)  as H = 14.514 > χ2 = 6.251, the level of creaminess is the same for all brands. 
A)  the alternative hypothesis should be rejected. 
B)  the null hypothesis should be accepted. 
C)  there is no difference in creaminess among the brands. 
D)  the null hypothesis should be rejected and at least one of the brands has a different distribution from the others. 
E)  as H = 14.514 > χ2 = 6.251, the level of creaminess is the same for all brands.

Question 10

Use the following to answer the question(s) below.
Preparing wheat for use in bread and pasta products generally involves both milling and bleaching. A company that processes wheat is interested in determining the best combination of milling and bleaching that results in a desirable wheat product without sacrificing fibre content. They vary the milling time (short, medium and long) and bleaching (no bleaching and bleaching) and measure fibre content (gms/100 grams) of the resulting wheat product. The partial ANOVA results apply.  
-The P-value associated with the F-statistic for the interaction effect is 0.18. Based on this we can conclude that

Accepted Answer

A)  there is a significant interaction effect. 
B)  since there is a significant interaction effect, bleaching and milling have no effect on fibre content. 
C)  the significance of the interaction effect will not influence the interpretation of the main effects on fibre content due to milling and bleaching. 
D)  there is a significant interaction effect, and it is not appropriate to interpret the main effects on fibre content due to milling and bleaching separately. 
E)  there is no significant interaction effect, and it is appropriate to interpret the main effects on fibre content due to milling and bleaching separately. 
A)  there is a significant interaction effect. 
B)  since there is a significant interaction effect, bleaching and milling have no effect on fibre content. 
C)  the significance of the interaction effect will not influence the interpretation of the main effects on fibre content due to milling and bleaching. 
D)  there is a significant interaction effect, and it is not appropriate to interpret the main effects on fibre content due to milling and bleaching separately. 
E)  there is no significant interaction effect, and it is appropriate to interpret the main effects on fibre content due to milling and bleaching separately.

Question 11

A quality assurance manager is interested in determining the likelihood that more than 20 calls come in to a particular customer service centre per hour. What method would be most appropriate for assigning this probability?

Accepted Answer

A)  Personal 
B)  Judgmental 
C)  Subjective 
D)  Relative Frequency (Empirical) 
E)  Classical (Theoretical) 
A)  Personal 
B)  Judgmental 
C)  Subjective 
D)  Relative Frequency (Empirical) 
E)  Classical (Theoretical)

Question 12

Use the following to answer the question(s) below.
A sample of 30-year fixed mortgage rates at 12 randomly chosen credit unions yields a mean rate of 6.65 % and a sample standard deviation of 0.39%. A sample of 30-year fixed mortgage rates at 16 randomly selected banks yields a mean rate of 7.05% and a sample standard deviation of 0.22%. Are the mean rates different between credit unions and banks? Relevant output is shown below.  
-At the 0.05 level of significance, the correct conclusion is

Accepted Answer

A)  reject the alternative hypothesis. 
B)  fail to reject the null hypothesis. 
C)  evidence suggests that there is no significant difference in mean mortgage rates between credit unions and banks. 
D)  reject the null hypothesis; evidence suggests that there is a significant difference in mean mortgage rates between credit unions and banks. 
E)  fail to reject the null hypothesis; evidence suggests that the mortgage rates at credit unions are lower than at banks, on average. 
A)  reject the alternative hypothesis. 
B)  fail to reject the null hypothesis. 
C)  evidence suggests that there is no significant difference in mean mortgage rates between credit unions and banks. 
D)  reject the null hypothesis; evidence suggests that there is a significant difference in mean mortgage rates between credit unions and banks. 
E)  fail to reject the null hypothesis; evidence suggests that the mortgage rates at credit unions are lower than at banks, on average.

Question 13

Use the following to answer the question(s) below.
IT staff for a large corporation has developed the following probability distribution for the number of calls requiring troubleshooting problems per day.
 
-The expected number of calls per day is

Accepted Answer

A)  2.77. 
B)  1.56. 
C)  1.21. 
D)  1.31. 
E)  1.0. 
A)  2.77. 
B)  1.56. 
C)  1.21. 
D)  1.31. 
E)  1.0.

Question 14

Suppose that a manufacturer is testing one of its machines to make sure that the machine is producing more than 97% good parts (H0: p = 0.97 and HA: p > 0.97). The test results in a P-value of 0.102. In reality, the machine is producing 99% good parts. What probably happens as a result of our testing?

Accepted Answer

A)  We correctly fail to reject H0. 
B)  We correctly reject H0. 
C)  We reject H0, making a Type I error. 
D)  We fail to reject H0, making a Type I error. 
E)  We fail to reject H0, making a Type II error. 
A)  We correctly fail to reject H0. 
B)  We correctly reject H0. 
C)  We reject H0, making a Type I error. 
D)  We fail to reject H0, making a Type I error. 
E)  We fail to reject H0, making a Type II error.

Question 15

Use the following to answer the question(s) below.
A newspaper poll asked respondents if they trusted "eco friendly" labels on cleaning products. Out of 1000 adults surveyed, 498 responded "yes." We would like to test if the proportion of respondents that trust these labels is at least 50%.
-The calculated test statistic value is

Accepted Answer

A)  -0.126. 
B)  -2.45. 
C)  1.27. 
D)  -1.89. 
E)  0.139. 
A)  -0.126. 
B)  -2.45. 
C)  1.27. 
D)  -1.89. 
E)  0.139.

Question 16

Use the following to answer the question(s) below.
A manufacturer of cordless electric shavers sampled 13 from a day's production and found the mean time of continuous usage without recharging to be 410 minutes with a sample standard deviation of 30 minutes. We can assume that times are normally distributed. We wish to test if the true mean operating time without recharging is more than 400 minutes.
-The correct value of the test statistic is

Accepted Answer

A)  1.20. 
B)  -0.333. 
C)  -2.52. 
D)  -1.20. 
E)  2.79. 
A)  1.20. 
B)  -0.333. 
C)  -2.52. 
D)  -1.20. 
E)  2.79.

Question 17

Use the following to answer the question(s) below.
A publishing company conducted a survey of its readership and found that 60% subscribed to Food & Wine, 30% subscribed to Wine Spectator, and 25% subscribed to both.
-The probability that a reader does not subscribe to either is

Accepted Answer

A)  0.10. 
B)  0.65. 
C)  0.50. 
D)  0.45. 
E)  0.35. 
A)  0.10. 
B)  0.65. 
C)  0.50. 
D)  0.45. 
E)  0.35.

Question 18

Use the following to answer the question(s) below.
A manufacturer of cordless electric shavers sampled 13 from a day's production and found the mean time of continuous usage without recharging to be 410 minutes with a sample standard deviation of 30 minutes. We can assume that times are normally distributed. We wish to test if the true mean operating time without recharging is more than 400 minutes.
-The correct null and alternative hypotheses are

Accepted Answer

A) H0: µ = 400; HA: µ 400. C) H0: µ > 400; HA: µ = 400. D) H0: µ < 400; HA: µ = 400. E) H0: µ = 400; HA: µ ≠ 400. A) H0: µ = 400; HA: µ 400. C) H0: µ > 400; HA: µ = 400. D) H0: µ < 400; HA: µ = 400. E) H0: µ = 400; HA: µ ≠ 400.

Question 19

Use the following to answer the question(s) below.
A government agency has 6000 employees. As an alternative to the traditional five day work week, employees were asked whether they preferred a four-day work week (10 hours per day) or flexible hours. The table below shows the results by age category.
  
-Two events F = {a randomly selected employee prefers flex hours} and O = {a randomly selected employee is over 45 years old} are

Accepted Answer

A)  independent. 
B)  mutually exclusive. 
C)  not independent. 
D)  independent and mutually exclusive. 
E)  disjoint. 
A)  independent. 
B)  mutually exclusive. 
C)  not independent. 
D)  independent and mutually exclusive. 
E)  disjoint.

Question 20

A human resources manager at a large company wants to estimate the proportion of employees that would be interested in reimbursement for college courses. If she wishes to be 95% confident that her estimate is within 5% of the true proportion, how many employees would need to be sampled?

Accepted Answer

A)  271 
B)  385 
C)  543 
D)  646 
E)  1234 
A)  271 
B)  385 
C)  543 
D)  646 
E)  1234

The following plot is the best for checking

Which of the following is not an assumption or condition that needs to be checked for a two-sample t-test for the difference between two means?

A type I error is committed when

A quality assurance manager is interested in determining the likelihood that more than 20 calls come in to a particular customer service centre per hour. What method would be most appropriate for assigning this probability?

Use the following to answer the question(s) below. IT staff for a large corporation has developed the following probability distribution for the number of calls requiring troubleshooting problems per day. -The expected number of calls per day is

Use the following to answer the question(s) below. A publishing company conducted a survey of its readership and found that 60% subscribed to Food & Wine, 30% subscribed to Wine Spectator, and 25% subscribed to both. -The probability that a reader does not subscribe to either is

A human resources manager at a large company wants to estimate the proportion of employees that would be interested in reimbursement for college courses. If she wishes to be 95% confident that her estimate is within 5% of the true proportion, how many employees would need to be sampled?

Data

Surveys and Sampling

Displaying and Describing Categorical Data

Displaying and Describing Quantitative Data

Scatterplots, Association, and Correlation

Introduction to Linear Regression

Randomness and Probability

Random Variables and Probability Distributions

Sampling Distributions

Confidence Intervals for Proportions

Testing Hypotheses About Proportions

Confidence Intervals and Hypothesis Tests for Means

Comparing Two Means

Design of Experiments and Analysis of Variance Anova

Inference for Counts: Chi-Square Tests

Nonparametric Methods

Inference for Regression

Understanding Regression Residuals

Multiple Regression

Building Multiple Regression Models

Time Series Analysis

Decision Making and Risk

Quality Control

Exploring and Collecting Data

Exploring Relationships Among Variables

Using Statistics for Decision Making

Filters

Exam 26: Understanding Probability Distributions and Statistical Inference

The following plot is the best for checking

Which of the following is not an assumption or condition that needs to be checked for a two-sample t-test for the difference between two means?

A type I error is committed when

A quality assurance manager is interested in determining the likelihood that more than 20 calls come in to a particular customer service centre per hour. What method would be most appropriate for assigning this probability?

Use the following to answer the question(s) below. IT staff for a large corporation has developed the following probability distribution for the number of calls requiring troubleshooting problems per day. -The expected number of calls per day is

Use the following to answer the question(s) below. A publishing company conducted a survey of its readership and found that 60% subscribed to Food & Wine, 30% subscribed to Wine Spectator, and 25% subscribed to both. -The probability that a reader does not subscribe to either is

A human resources manager at a large company wants to estimate the proportion of employees that would be interested in reimbursement for college courses. If she wishes to be 95% confident that her estimate is within 5% of the true proportion, how many employees would need to be sampled?

Data

Surveys and Sampling

Displaying and Describing Categorical Data

Displaying and Describing Quantitative Data

Scatterplots, Association, and Correlation

Introduction to Linear Regression

Randomness and Probability

Random Variables and Probability Distributions

Sampling Distributions

Confidence Intervals for Proportions

Testing Hypotheses About Proportions

Confidence Intervals and Hypothesis Tests for Means

Comparing Two Means

Design of Experiments and Analysis of Variance Anova

Inference for Counts: Chi-Square Tests

Nonparametric Methods

Inference for Regression

Understanding Regression Residuals

Multiple Regression

Building Multiple Regression Models

Time Series Analysis

Decision Making and Risk

Quality Control

Exploring and Collecting Data

Exploring Relationships Among Variables

Using Statistics for Decision Making

Filters