Compute the following sample sizes. Use the appropriate formula. If necessary, round to the nearest hundredth A random sample of 32 retail stocks such as Toys ‘R’ Us, Best Buy , and Gap were studied for x1, profit as a percentage of stockholder equity. The result was ?̅1 = 13.7. A random sample of 34 utility (gas and electric) stocks such as Boston Edison, Wisconsin Energy, and Texas Utilities, were studied for x2, profit as a percentage of stockholder equity. The result was ?̅2 = 10.1. (Source: Fortune 500, Vol. 135, No. 8.) Assume that ?1 = 4.1 and ?2 = 2.7. a. Let ?1 represent the population mean profit as a percentage of stockholder equity for retail stocks, and let ?2 represent the population mean profit as a percentage of stockholder equity for utility stocks. Find a 95% confidence interval for ?1 − ?2 (by the calculator). b. Explain what this interval means in the context of this problem. Can we make any conclusion comparing μ1and μ2
Compute the following sample sizes. Use the appropriate formula. If
necessary, round to the nearest hundredth
A random sample of 32 retail stocks such as Toys ‘R’ Us, Best Buy , and Gap were studied for x1,
profit as a percentage of stockholder equity. The result was ?̅1 = 13.7. A random sample of 34
utility (gas and electric) stocks such as Boston Edison, Wisconsin Energy, and Texas Utilities, were
studied for x2, profit as a percentage of stockholder equity. The result was ?̅2 = 10.1. (Source:
Fortune 500, Vol. 135, No. 8.) Assume that ?1 = 4.1 and ?2 = 2.7.
a. Let ?1 represent the population mean profit as a percentage of stockholder equity for retail
stocks, and let ?2 represent the population mean profit as a percentage of stockholder equity
for utility stocks. Find a 95% confidence interval for ?1 − ?2 (by the calculator).
b. Explain what this interval means in the context of this problem. Can we make any conclusion
comparing μ1and μ2
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