many grocery stores and large retailers such as kroger and walmart have installed self-checkout systems so shoppers can scan their own items and cash out themselves. how do customers like this service and how often do they use it? listed is the number of customers using the service for a sample of 15 days at a walmart location. is it reasonable to conclude that the mean number of customers using the self-checkout system is more than 100 per day? use the 0.05 significance level.