Chapter 12 Practice Test

Name:

Multiple Choice
Identify the choice that best completes the statement or answers the question.

In an opinion poll, 25% of a random sample of 200 people said that they were strongly opposed to having a state lottery. The standard error of the sample proportion is approximately

a.	0.03
b.	0.25
c.	0.0094
d.	6.12
e.	0.06

You want to design a study to estimate the proportion of students on your campus who agree with the statement, “The student government is an effective organization for expressing the needs of students to the administration.” You will use a 95% confidence interval and you would like the margin of error to be 0.05 or less. The minimum sample size required is approximately

a.	22
b.	1795
c.	385
d.	271
e.	None of the above.

An opinion poll asks a random sample of adults whether they favor banning ownership of handguns by private citizens. A commentator believes that more than half of all adults favor such a ban. The null and alternative hypotheses you would use to test this claim are:

a.
b.
c.
d.
e.	None of the above.

An SRS of size 100 is taken from a population having proportion 0.8 successes. An independent SRS of size 400 is taken from a population having proportion 0.5 successes. The sampling distribution of the difference in sample proportions has what mean?

a.	0.3
b.	0.15
c.	The smaller of 0.8 and 0.5
d.	The mean cannot be determined without the sampling results.
e.	None of the above.

The college newspaper of a large Midwestern university periodically conducts a survey of students on campus to determine the attitude on campus concerning issues of interest. Pictures of the students interviewed along with quotes of their responses are printed in the paper. Students are interviewed by a reporter “roaming” the campus selecting students to interview “haphazardly.” On a particular day the reporter interviews five students and asks them if they feel there is adequate student parking on campus. Four of the students say no.

Which of the following conditions for inference about a proportion using a confidence interval are violated in this example?

a.	The data are an SRS from the population of interest.
b.	The population is at least ten times as large as the sample.
c.	10 and .
d.	We are interested in inference about a proportion.
e.	More than one condition is violated.

A 95% confidence interval for p, the proportion of Canadian beer drinkers who prefer Lion Red was found to be (0.236,0.282). Which of the following is correct?

a.	About 95% of beer drinkers have between a 23.6% and a 28.2% chance of drinking Lion Red.
b.	There is a 95% probability that the sample proportion lies between 0.236 and 0.282.
c.	If a second sample was taken, there is a 95% chance that its confidence interval would contain 0.25.
d.	This confidence interval indicates that we would likely reject the hypothesis H₀: p = 0.25.
e.	We are reasonably certain that the true proportion of beer drinkers who prefer Lion Red is between 24% and 28%.

In a large Midwestern university (the class of entering freshmen being on the order of 6000 or more students), an SRS of 100 entering freshmen in 1993 found that 20 finished in the bottom third of their high school class. Admission standards at the university were tightened in 1995. In 1997 an SRS of 100 entering freshmen found that 10 finished in the bottom third of their high school class. Let p₁ and p₂ be the proportion of all entering freshmen in 1993 and 1997, respectively, who graduated in the bottom third of their high school class.

What conclusion should we draw?

a.	We are 95% confident that the admissions standards have been tightened.
b.	Reject H₀ at the = 0.01 significance level.
c.	Fail to reject H₀ at the = 0.05 significance level.
d.	There is significant evidence of a decrease in the proportion of freshmen who graduated in the bottom third of their high school class that were admitted by the university.
e.	If we reject H₀ at the = .05 significance level based on these results, we have a 5% chance of being wrong.

A radio talk show host with a large audience is interested in the proportion p of adults in his listening area think the drinking age should be lowered to eighteen. To find this out, he poses the following question to his listeners. “Do you think that the drinking age should be reduced to eighteen in light of the fact that eighteen-year-olds are eligible for military service?” He asks listeners to phone in and vote “yes” if they agree the drinking age should be lowered and “no” if not. You are told that the proportion

of those who phoned in and answered “yes” is

= 0.70, and the standard error SE of the proportion is 0.0459. The number of people who phoned in

a.	is 50.
b.	is 99.
c.	is 100.
d.	is 200.
e.	cannot be determined from the information given.

In a poll, (a) some people refused to answer questions, (b) people without telephones could not be in the sample, and (c) some people never answered the phone in several calls. Which of these sources is included in the ±2% margin of error announced for the poll?

a.	Only source (a).
b.	Only source (b).
c.	Only source (c).
d.	All three sources of error.
e.	None of these sources of error.

10.

A polling organization announces that the proportion of American voters who favor congressional term limits is 64 %, with a 95% confidence margin of error of 3%. If the opinion poll had announced the margin of error for 80% confidence rather than 95% confidence, this margin of error would be

a.	3%, because the same sample is used.
b.	Less than 3%, because we require less confidence.
c.	Less than 3%, because the sample size is smaller.
d.	Greater than 3%, because we require less confidence.
e.	Greater than 3%, because the sample size is smaller.