The number of undergraduates at Johns Hopkins University is approximately 2000, while the number at Ohio State University is approximately 40,000. At both schools, a simple random sample of about 3%of the undergraduates is taken. Each sample is used to estimate the proportion p of all students at that university who own an iPod. Suppose that, in fact, p=0.80at both schools. Which of the following is the best conclusion?

(a) The estimate from Johns Hopkins has less sampling variability than that from Ohio State.

(b) The estimate from Johns Hopkins has more sampling variability than that from Ohio State.

(c) The two estimates have about the same amount of sampling variability.

(d) It is impossible to make any statement about the sampling variability of the two estimates since the students surveyed were different.

(e) None of the above

Short Answer

Expert verified

The correct answer is (b) The estimate from Johns Hopkins has more sampling variability than that from Ohio State.

Step by step solution

01

Given Information

Given the number of undergraduates at Johns Hopkins University =2000

Number of undergraduates at Ohio State University=40,000

Percent of undergraduates for a sample=3%

Proportion of students who own an iPod,p=0.80

Given that each university has 3%students who own iPod.

02

Explanation

Consider that the sample of students from Johns Hopkins University be nЈнand the sample of students from Ohio State University be n_{0S}.

Since the number of undergraduates of John Hopkins University is less than the number of undergraduates of Ohio State University; so, nJH<nOS

Know that if the sample size is larger, then it gives more information about the population and it has less sampling variability. This means the estimate from Johns Hopkins University has more sampling variability than that from Ohio State.

Hence, the correct answer is (b).

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Most popular questions from this chapter

You work for an advertising agency that is preparing a new television commercial to appeal to women. You have been asked to design an experiment to compare the effectiveness of three versions of the commercial. Each subject will be shown one of the three versions and then asked about her attitude toward the product. You think there may be large differences between women who are employed and those who are not. Because of these differences, you should use

(a) a block design, but not a matched pairs design

(b) a completely randomized design.

(c) a matched pairs design.

(d) a simple random sample.

(e) a stratified random sample.

(a) Sketch a possible graph of the distribution of sample data for an SRS of size 5 with a range of 1000grams.

(b) Explain why the dotplot of sample ranges above is not the actual sampling distribution of the sample range.

The gypsy moth is a serious threat to oak and aspen trees. A state agriculture department places traps throughout the state to detect the moths. When traps are checked periodically, the mean number of moths trapped is only 0.5,but some traps have several moths. The distribution of moth counts is discrete and strongly skewed, with standard deviation0.7.

(a) What are the mean and standard deviation of the average number of moths xin50traps?

(b) Use the central limit theorem to help you find the probability that the average number of moths in 50traps is greater than0.6.

IRS audits The Internal Revenue Service plans to examine an SRS of individual federal income tax returns from each state. One variable of interest is the proportion of returns claiming itemized deductions. The total number of tax returns in each state varies from over 15 million in California to about 240,000in Wyoming.

(a) Will the sampling variability of the sample proportion change from state to state if an SRS of 2000tax returns is selected in each state? Explain your answer.

(b) Will the sampling variability of the sample proportion change from state to state if an SRS of 1%of all tax returns is selected in each state? Explain your answer

Doing homework Refer to Exercise 9.

(a) Make a graph of the population distribution given that there are 3000 students in the school. (Hint: What type of variable is being measured?)

(b) Sketch a possible graph of the distribution of sample data for the SRS of size 100 taken by the AP Statistics students.

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