Practice Problems Two Population T

Practice Problems Two Population T - T wo Population T-Test...

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Two Population T-Test Eddie Clauer sells a wide variety of outdoor equipment and clothing. The company sells both through mail order and via the internet. Random samples of sales receipt were studied for the mail-order sales and the internet sales, with the total purchase being recorded for each sale. A random sample of 6 sales receipts for mail-order sales results in a mean sale amount of \$79.90, with a standard deviation of \$22.25. A random sample of 16 sales receipts for internet sales results in a mean sale amount of \$95.10, with a standard deviation of \$16.75. Using this data, find the 80% confidence interval for the true mean difference between the mean amount of mail-order purchases and the mean amount of internet purchases. Assume that the population variances are not equal and the two populations are normally distributed. Given two independent random samples with the following results: n1 11 n2 7 x1 119 x2 158 s1 30 s2 16 Use this data to find the 95% confidence interval for the true difference between the population means. Assume that the population variances are equal and the populations are normally distributed. A manufacturer claims that the calling range (in feet) of its 900 MHz cordless telephones is greater than that of its leading competitor. A sample of 16 phones from the manufacturer had a mean range of 1380 feet with a standard deviation of 31 feet. A sample of 10 similar phones from its competitor had a mean range of 1370 feet with a standard deviation of 34 feet. Do the results support the manufacturers claim? Use a significance level of 0.05 for the test. Assume that the population variances are equal and that the two populations are normally distributed.

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Dependent (Paired T-test) The U.S. Census Bureau collects census on the ages of married people. Suppose that eight married couples are randomly selected and have the ages given in the following table.
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