Test #13 (Chapter 14)Honor Pledge ______

AP StatisticsName ______

4/3/08Wood/MyersPeriod ______

Test #13 (Chapter 14)Honor Pledge ______

Part I - Multiple Choice (Questions 1-10) – Bubble the answer of your choice on the scantron form.

Questions 1 to 3 relate to the following situation.

A sample of 102 drug users was interviewed and each subject was asked to name the kind of drug that each first injected. Here are the results:
First drug injectedNumber

Heroin42

Speed36

Other24

1.An appropriate null hypothesis is

(a)the count of first drug injected is the same for each drug category.

(b)µ = 34.

(c)at least one of the cell counts is different from the other two.

(d)the proportion of first drug injected depends on the type of drug.

(e)the 3 cell counts are independent of the type of drug.

2.The test statistic, degrees of freedom, and P-value are

(a)4.94,2, 0.0845.

(b)1.88, 2, 0.391.

(d) 0.118, 2, 0.94.

(e) 8.94, 2, 0.011.

3.Which of the following is a correct statement? In order to make an inference about the population,

(a)the population has to be at least 10 times the size of the sample.

(b)the cell counts for our sample have to be approximately the same as the counts for the host population.

(c)all observed cell counts have to be positive, and no more than 20% can be less than 15.

(d)the sample has to have the same characteristics as the population.

(e)the subjects have to be a random sample of drug users.

4.Are all employees equally prone to having accidents? To investigate this hypothesis, a researcher looked at a light manufacturing plant and classified the accidents by type and by age of the employee.

Accident Type

Age Sprain Burn Cut

Under 25 9 17 5

25 or over 61 13 12

A chi-square test gave a test statistic of 20.78. If we test at  = 0.05

(a) there appears to be no association between accident type and age.

(b) age seems to be independent of accident type.

(d) there appears to be a 20.78% correlation between accident type and age.

(e) the proportion of sprain, cuts, and burns seems to be similar for both age classes.

5.A chi-square goodness of fit test is used to test whether a 0 to9 spinner is “fair” (that is, the outcomes are all equally likely). The spinner is spun 100 times, and the results are recorded. Which member of the chi-square family of curves is used?

(a)

(b)

6.Each person in a random sample of 50 was asked to state his/her sex and preferred color. The resulting frequencies are shown below.

Color

Red Blue Green

Male 5 14 6

Female 15 6 4

A chi-square test is used to test the null hypothesis that sex and preferred color are independent. Which of the following statements is a correct decision about the null hypothesis?

(a) Reject at the 0.005 level.

(b) Reject at the 0.01 level but not at the 0.005 level.

(d) Reject at the 0.05 level but not at the 0.025 level.

(e) Accept at the 0.05 level.

7.The following data were obtained from a company that manufactures special plastic containers that are to hold a specified volume of hazardous material. On each of the three 8-hour shifts workers are able to make 500 of the containers. Some containers do not meet specifications as required by the company’s customer because they are too small; others, because they are too large.

Conformance to Specification

Shift Too small Within spec. Too large

8 am36 452 12

4 pm24 443 33

Midnight 12 438 50

The appropriate inference procedure to use to analyze this information would be:

(a) goodness-of-fit test

(b) Two-proportion z-test

(d) Double correlation test of simplicity

(e) test of independence

8.A survey was conducted to investigate whether alcohol consumption and smoking are related. The following information was compiled for 600 individuals:

Smoker Nonsmoker

Drinker 193 165

Nondrinker 89 153

Which of the following statements is true?

(a) The appropriate alternative hypothesis is Ha: Smoking and alcohol consumption are independent.

(b) The appropriate null hypothesis is H0: Smoking and alcohol consumption are not independent.

(d) The calculated value of the test statistic is 7.86.

(e) At level 0.01 we conclude that smoking and alcohol consumption are related.

9.A controversial issue in sports is the use of the “instant replay” for making decisions on plays that are extremely close or hard to call by an official. A random survey of players in each of four professional sports was conducted, asking them if they felt instant replays should be used to decide close or controversial calls. The results are as follows:

Use of Instant Replay

Favor Oppose

Football 22 2

Baseball 18 6

Basketball 15 26

Soccer 3 10

In testing to see whether opinion with respect to the use of instant replays is independent of sport, a table of expected frequencies is found. In this table, the expected number of professional baseball players opposing the use of instant replays is equal to:

(a) 10.4 (b) 24.1(c) 11.0(d) 6.0(e) 8.4

10.A study of accident records at a large engineering company in England reported the following number of injuries on each shift for 1 year:

Shift:Morning Afternoon Night

Number of injuries:137215781686

Is there sufficient evidence to say that the numbers of accidents on the three shifts are not the same? Test at the 0.05, 0.01, and 0.001 levels.

(a) There is sufficient evidence at all three levels to say that the numbers of accidents on each shift are not the same.

(b) There is sufficient evidence at the 0.05 and 0.01 levels but not at the 0.001 level.

(d) There is sufficient evidence at the 0.001 level but not at the 0.01 or 0.05 levels.

(e)There is insufficient evidence at any of these levels.

Part II – Free Response (Questions 11-12) – Show your work and explain your results clearly.

11.Births are not evenly distributed across the days of the week. Fewer babies are born on Saturday and Sunday than on other days, probably because doctors find weekend births inconvenient. A random sample of 700 births from local records shows this distribution across the days of the week:

Day Sun. Mon. Tue. Wed. Thu. Fri. Sat.

Births 84 110 124 104 94 112 72

Does the given data provide significant evidence that births are not equally probable on all days of the week? Give statistical evidence to support your findings.

12.A sample survey by the Pew Internet and American Life Project asked a random sample of adults about use of the Internet and about the type of community they lived in. Here are the results:

Community Type

RuralSuburbanUrban

Internet users433 1072536

Nonusers463 627388

Is there a relationship between Internet use and community type? Give statistical evidence to support your findings.