Question

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 receipts were studied for mail-order sales and internet sales, with the total purchase being recorded for each sale. A random sample of 99 sales receipts for mail-order sales results in a mean sale amount of $96.00$⁢96.00 with a standard deviation of $24.25$⁢24.25. A random sample of 1919 sales receipts for internet sales results in a mean sale amount of $83.90$⁢83.90 with a standard deviation of $29.75$⁢29.75. Using this data, find the 90%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 standard error of the sampling distribution to be used in constructing the confidence interval. Round your answer to two decimal places.

Answer 1