Reconsider the previous exercises.
a. If the waitress had used larger sample sizes (say, 40 in each group) and the sample means and SDs had turned out the same as they did in the study originally, what impact would you expect this to have on the test statistic, p-value, and confidence interval?

b. Make this change and report the new test statistic, p-value, and confidence interval. Was the impact what you expected?

Data from previous exercise

Can waitresses increase their tips simply by introducing  themselves by name when they greet customers? A waitress collected data on two-person parties that she waited on during Sunday brunch (with a fixed price of $23.21) at a Charley Brown’s restaurant in southern California. For each party the waitress used a random mechanism to determine whether to give her name as part of her greeting or not. Then she kept track of how much the party gave for a tip at the end of their meal.