Question

J.J.Bean 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 16 sales receipts for mail-order sales results in a mean sale amount of $⁢83.10 with a standard deviation of $⁢25.75. A random sample of 12 sales receipts for internet sales results in a mean sale amount of $⁢78.10 with a standard deviation of $⁢16.25. Using this data, find the 95% 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 1 of 3:

Find the point estimate that should be used in constructing the confidence interval.

Step 2 of 3:

Find the margin of error to be used in constructing the confidence interval. Round your answer to six decimal places.

Step 3 of 3:

Construct the 95% confidence interval. Round your answers to two decimal places.

Answer 1

i am denoting the two sample by 1 and 2 respectively.

given data are:-

.

1).the point estimate that should be used in constructing the confidence interval is:-

2).degrees of freedom :-

t critical value for df=25,alpha= 0.05, both tailed test be:-

[ using t distribution table]

the margin of error to be used in constructing the confidence interval is:-

3).the 95% confidence interval is :-

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