Question

Land's Bend sells a wide variety of outdoor equipment and clothing. The company sells both through mail order and via the internet. Random samples of sales receipts were studied for mail-order sales and internet sales, with the total purchase being recorded for each sale. A random sample of 9 sales receipts for mail-order sales results in a mean sale amount of $95.50 with a standard deviation of $27.25. A random sample of 16 sales receipts for internet sales results in a mean sale amount of $85.50 with a standard deviation of $22.25. Using this data, find the 90% 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 that the two populations are normally distributed.

Step 2 of 3 : Find the margin of error to be used in constructing the confidence interval. Round your answer to six decimal places. point of estimate= 10

Answer 1

Confidence interval :-

t(α/2, DF) = t(0.1 /2, 14 ) = 1.761

DF = 14


Lower Limit =
Lower Limit = -8.7568
Upper Limit =
Upper Limit = 28.7568
90% Confidence interval is ( -8.7568 , 28.7568 )

Step 2

Margin of Error =