Target versus Walmart: Who has the lowest prices? Given Walmart's slogan "Save Money-Live Better," you suspect that Walmart does. In order to test your suspicion, you identify 20 items (all brand-name items) currently on your household shopping list. You visit both Target and Walmart, price each item, and organize and store these data in Target Walmart.
a. At the 0.05 level of significance, is there evidence that the mean price of items is higher at Target than at Walmart?
b. What assumption is necessary about the population distribution in order to perform this test?
c. Find the p-value in (a) and interpret its meaning.