The owner of a pizza restaurant in France knows that the time customers spend in the restaurant on Saturday evening has mean 90 minutes and standard deviation 15 minutes. He has read that pleasant odors can influence customers, so he spreads a lavender odor throughout the restaurant. Here are the times (minutes) for customers on the next Saturday evening:15
(a) Make a stemplot of the times. The distribution is roughly symmetric and single-peaked, so the distribution of should be close to Normal.
(b) Suppose that the standard deviation σ = 15 minutes is not changed by the odor. Is there reason to think that the lavender odor has changed the mean time customers spend in the restaurant? Follow the four-step process for significance tests (page 379).