A department store sells a broad range of household products and offers a low-cost breakfast in its store restaurants to attract customers into the stores early in the day. A manager of one of these stores is making a loss on the breakfasts. He needs to know whether the breakfast attracts customers to shop for the more profitable household items, and he decides to calculate the correlation between the number of customers taking breakfast and the number buying household items. Analyze the following sample data that are collected during the course of one week. Complete parts (a) through (b) below.

 

a) What is the correlation coefficient over the whole week? The correlation coefficient is (Round to four decimal places as needed.)

b) What is the correlation coefficient over the weekdays only? The correlation coefficient is (Round to four decimal places as needed.)

Day Monday Tuesday Wednesday Thursday Friday Saturday Sunday Customers Buying Customers Buying Household Items Breakfast 70 53 57 82 85 292 248 50 46 26 57 36 280 227