Question: 5.1 A market analyst studying the length of time shoppers spend in two types of grocery store observes a sample of 75 shoppers in each store. The mean time the sample of shoppers spend in Store A is 55 minutes. The mean time the sample of shoppers spend in Store B is 49 minutes. What is the probability of observing a sample difference \({{\bar{x}}_{A}}-{{\bar{x}}_{B}}\) least as large as and in the same direction as this if there is no difference in the true mean time that shoppers spend in the two stores and if the standard deviation is 15 minutes for both populations? What assumptions are made regarding the samples?