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Standard errors and difference in proportion

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1. Find the standard error of the mean for each sampling situation (assuming a normal population).
What happens to the standard error each time you quadruple the sample size?
a. sigma = 32, n = 4
b. sigma = 32, n = 16
c. sigma = 32, n = 64

2. The American Bankers Association reports that, in a sample of 120 consumer purchases in France, 60 were made with cash, compared with 26 in a sample of 50 consumer purchases in the United States. Construct a 90 percent confidence interval for the difference in proportions.
(Data are from The Wall Street Journal, July 27, 2004.)

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Solution Summary

This solution shows how to calculate the standard error of a sample mean and how to construct a confidence interval for the difference between two population proportions.

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This solution shows how to calculate the standard error of a sample mean and how to construct a confidence interval for the difference between two population proportions.

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1. Find the standard error of the mean for each sampling situation (assuming a normal population).
What happens to the standard error each time you quadruple the sample size?
a. σ = 32, n = 4 ...

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