# Confidence Co-Efficients

Olive Garden Swiss Chalet

Sample size 50 45

Sample mean $22 $18

Standard deviation $3.00 $3.25

How do I create interval estimate for the difference between the average fees of the 2 restaurants at a confidence co-effiecent at 95 %

What do I need to do to find out the difference in amount spent at the restaurants (sample means)? What test statistic do I use? I thought I should use the z-test because the sample size was greater than 30.

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#### Solution Preview

This is a test of difference in sample means

Usually we use t test, but in this question you might use z stat as well, given the large sample size.

Find the 95% confidence interval for the difference between the two means

Let Md=µ1-µ2= 22-18 = 4

In the general formula, the estimated standard error, SMd, is computed assuming that the variances in the two populations are equal. when n1 ≠ n2. The ...

#### Solution Summary

The expert determines how to create interval estimate for the difference between the average fees of the 2 restaurants at a confidence coefficient at 95 %

What do I need to do to find out the difference in amount spent at the restaurants (sample means)? What test statistic do I use? I thought I should use the z-test because the sample size was greater than 30.