Question

J.J.Bean sells a wide variety of outdoor equipment and clothing. The company sells both in-store and online. Random samples of sales receipts were studied for in-store sales and online sales, with the total purchase being recorded for each sale. A random sample of 20 sales receipts for in-store sales results in a mean sale amount of $92.90 with a standard deviation of $22.75. A random sample of 10 sales receipts for online sales results in a mean sale amount of $77.50 with a standard deviation of $26.25. Using this data, find the 99% confidence interval for the true mean difference between the mean amount of in-store purchases and the mean amount of online purchases. Assume that the population variances are not equal and that the two populations are normally distributed.

Step 1 of 3: Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

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.

Step 3 of 3: Construct the 99% confidence interval. Round your answers to two decimal places.

Answer 1