Question 1

According to the 2010 census, 20.3% of the population of the United States (ages 5 and up) live in a home in which a language other than English is spoken. Advocates for providing government programs to assist non-English speakers are convinced that, with the increasing non-white population in the United States, this proportion has probably increased. They plan to conduct a survey, and if they find the proportion of people who live in such homes has increased, they will organize a campaign to increase government investment in these assistance programs.
-In the larger sample the proportion of people living in a home in which a language other than English is spoken was 20.8%. The consultant decided this increase was statistically significant. Now that the group is convinced the proportion has increased, why might they still choose not to organize the campaign?

Accepted Answer

The answer of According to the 2010 census, 20.3% of...

Question 2

Employment program A city council must decide whether to fund a new
"welfare-to-work" program to assist long-time unemployed people in finding jobs. This
program would help clients fill out job applications and give them advice about dealing with job interviews. A six-month trial has just ended. At the start of this trial a number of unemployed residents were randomly divided into two groups; one group went through the help program and the other group did not. Data about employment at the end of this
trial are shown in the table. Should the city council fund this program? Test an appropriate hypothesis and state your conclusion. $\begin{array}{|c|c|c|}
\hline&{\text { Current job status }} \
\hline & \text { Employed } & \text { Unemployed } \
\hline \begin{array}{c}
\text { Group 1 } \
\text { (Help program) }
\end{array} & 20 & 34 \
\hline \begin{array}{c}
\text { Group 2 } \
\text { (No help) }
\end{array} & 13 & 33 \
\hline
\end{array}$

Accepted Answer

The answer of Employment program A city council must decide...

Question 3

Baldness and heart attacks A recent medical study observed a higher frequency of heart attacks among a group of bald men than among another group of men who were not bald. Based on a P-value of 0.062 the researchers concluded there was some evidence that male baldness may be a risk factor for predicting heart attacks. Explain in context what their
P-value means.

Accepted Answer

The answer of Baldness and heart attacks A recent medical...

Question 4

According to the 2010 census, 20.3% of the population of the United States (ages 5 and up) live in a home in which a language other than English is spoken. Advocates for providing government programs to assist non-English speakers are convinced that, with the increasing non-white population in the United States, this proportion has probably increased. They plan to conduct a survey, and if they find the proportion of people who live in such homes has increased, they will organize a campaign to increase government investment in these assistance programs.
-Write the advocates' null and alternative hypotheses.

Accepted Answer

The answer of According to the 2010 census, 20.3% of...

Question 5

The International Olympic Committee states that the female participation in the 2004 Summer Olympic Games was 42%, even with new sports such as weight lifting, hammer throw, and modern pentathlon being added to the Games. Broadcasting and clothing companies want to change their advertising and marketing strategies if the female participation increases at the next games. An independent sports expert arranged for a random sample of pre-Olympic exhibitions. The sports expert reported that 202 of 454 athletes in the random sample were women. Is this strong evidence that the participation rate may increase?

-Was your test one-tail upper tail, lower tail, or two-tail? Explain why you choose that kind of test in this situation.

Accepted Answer

The answer of The International Olympic Committee states that the...

Question 6

Tax advice Each year people who have income file income tax reports with the government. In some instances people seek advice from accountants and financial advisors regarding their income tax situations. This advice is meant to lower the percentage of taxes paid to the government each year. A random sample of people who filed tax reports resulted in the data in the table below. Does this data indicate that people should seek tax advice from an accountant or financial advisor? Test an appropriate hypothesis and state your conclusion. $\begin{array}{|c|c|c|}
\hline&{\text { Had Tax Advice? }} \
\hline \begin{array}{c}
\text { Paid Lower } \% \
\text { of taxes }
\end{array} & \text { No } & \text { Yes } \
\hline \text { No } & 48 & 19 \
\hline \text { Yes } & 24 & 86 \
\hline
\end{array}$

Accepted Answer

The answer of Tax advice Each year people who have...

Question 7

Internet access A recent Gallup poll found that 28% of U.S. teens aged 13-17 have a computer with Internet access in their rooms. The poll was based on a random sample of
1028 teens and reported a margin of error of ±3%. What level of confidence did Gallup use for this poll?

Accepted Answer

The answer of Internet access A recent Gallup poll found...

Question 8

The board of directors for Procter and Gamble is concerned that only 19.5% of the people who use toothpaste buy Crest toothpaste. A marketing director suggests that the company invest in a new marketing campaign which will include advertisements and new labeling for the toothpaste. The research department conducts product trials in test markets for one month to determine if the market share increases with new labels.
-Write the company's null and alternative hypotheses.

Accepted Answer

The answer of The board of directors for Procter and...

Question 9

The board of directors for Procter and Gamble is concerned that only 19.5% of the people who use toothpaste buy Crest toothpaste. A marketing director suggests that the company invest in a new marketing campaign which will include advertisements and new labeling for the toothpaste. The research department conducts product trials in test markets for one month to determine if the market share increases with new labels.
-The board of directors asked the research department to extend the trial period so that the decision can be made on two months worth of data. Will the power increase, decrease, or remain the same?

Accepted Answer

The answer of The board of directors for Procter and...

Question 10

Sleep Do more than 50% of U.S. adults feel they get enough sleep? According to Gallup's December 2004 Lifestyle poll, 55% of U.S. adults said that that they get enough sleep. The poll was based on a random sample of 1003 U.S. adults. Test an appropriate hypothesis and state your conclusion in the context of the problem.

Accepted Answer

The answer of Sleep Do more than 50% of U.S....

Question 11

A report on health care in the US said that 28% of Americans have experienced times when they haven't been able to afford medical care.  A news organization randomly sampled 801 black Americans, of whom 38% reported that there had been times in the last year when they had not been able to afford medical care.  Does this indicate that this problem is more severe among black Americans?
-Was your test one-tail upper tail, one-tail lower tail, or two-tail? Explain why you chose that kind of test in this situation.

Accepted Answer

The answer of A report on health care in the...

Question 12

A state's Department of Education reports that 12% of the high school students in that state attend private high schools. The State University wonders if the percentage is the same in their applicant pool. Admissions officers plan to check a random sample of the over 10,000 applications on file to estimate the percentage of students applying for admission who attend private schools.
-Interpret the confidence interval in this context.

Accepted Answer

The answer of A state's Department of Education reports that...

Question 13

A company manufacturing computer chips finds that 8% of all chips manufactured are defective. Management is concerned that employee inattention is partially responsible for the high defect rate. In an effort to decrease the percentage of defective chips, management decides to offer incentives to employees who have lower defect rates on their shifts. The incentive program is instituted for one month. If successful, the company will continue with the incentive program.
-In this context describe a Type I error and the impact such an error would have on the company.

Accepted Answer

The answer of A company manufacturing computer chips finds that...

Question 14

A company manufacturing computer chips finds that 8% of all chips manufactured are defective. Management is concerned that employee inattention is partially responsible for the high defect rate. In an effort to decrease the percentage of defective chips, management decides to offer incentives to employees who have lower defect rates on their shifts. The incentive program is instituted for one month. If successful, the company will continue with the incentive program.
-Management decided to extend the incentive program so that the decision can be made on three months of data instead. Will the power increase, decrease, or remain the same?

Accepted Answer

The answer of A company manufacturing computer chips finds that...

Question 15

Wildlife scientists studying a certain species of frogs know that past records indicate the adults should weigh an average of 118 grams with a standard deviation of 14 grams. The researchers collect a random sample of 50 adult frogs and weigh them. In their sample the mean weight was only 110 grams. One of the scientists is alarmed, fearing that environmental changes may be adversely affecting the frogs. Do you think this sample result is unusually low? Explain.

Accepted Answer

The answer of Wildlife scientists studying a certain species of...

Question 16

Explain what your P-value means in this context.

Accepted Answer

The answer of Explain what your P-value means in this...

Question 17

A company manufacturing computer chips finds that 8% of all chips manufactured are defective. Management is concerned that employee inattention is partially responsible for the high defect rate. In an effort to decrease the percentage of defective chips, management decides to offer incentives to employees who have lower defect rates on their shifts. The incentive program is instituted for one month. If successful, the company will continue with the incentive program.
-In this context describe a Type II error and the impact such an error would have on the company.

Accepted Answer

The answer of A company manufacturing computer chips finds that...

Question 18

The owner of a small clothing store is concerned that only 28% of people who enter her store actually buy something. A marketing salesman suggests that she invest in a new line of celebrity mannequins (think Seth Rogan modeling the latest jeans…). He loans her several different "people" to scatter around the store for a two-week trial period. The owner carefully counts how many shoppers enter the store and how many buy something so that at the end of the trial she can decide if she'll purchase the mannequins.  She'll buy the mannequins if there is evidence that the percentage of people that buy something increases.
-In this context describe a Type I error and the impact such an error would have on the store.

Accepted Answer

The answer of The owner of a small clothing store...

Question 19

According to the 2010 census, 20.3% of the population of the United States (ages 5 and up) live in a home in which a language other than English is spoken. Advocates for providing government programs to assist non-English speakers are convinced that, with the increasing non-white population in the United States, this proportion has probably increased. They plan to conduct a survey, and if they find the proportion of people who live in such homes has increased, they will organize a campaign to increase government investment in these assistance programs.
-A consultant talked the group into gathering a larger sample. Will the power of the test increase, decrease, or remain the same?

Accepted Answer

The answer of According to the 2010 census, 20.3% of...

Question 20

The board of directors for Procter and Gamble is concerned that only 19.5% of the people who use toothpaste buy Crest toothpaste. A marketing director suggests that the company invest in a new marketing campaign which will include advertisements and new labeling for the toothpaste. The research department conducts product trials in test markets for one month to determine if the market share increases with new labels.
-In this context describe a Type I error and the impact such an error would have on the company.

Accepted Answer

The answer of The board of directors for Procter and...

Quiz 5: Understanding and Comparing Distributions

Internet access A recent Gallup poll found that 28% of U.S. teens aged 13-17 have a computer with Internet access in their rooms. The poll was based on a random sample of 1028 teens and reported a margin of error of ±3%. What level of confidence did Gallup use for this poll?

Explain what your P-value means in this context.