Do consumers spend more on a trip to Store A or Store B? Suppose researchers interested in this question collected a systematic
sample for 85 Store A customers and 82 Store B customers by asking customers for their purchase amount as they left the store. Using the given summary statistics, researchers calculated a 95% confidence interval for the mean difference between Store A and Store B purchase amounts. The interval was ($negative 15.96,$negative 4.04). Explain in context what this interval means.