10.8. A locally owned department store samples two customers in each of five geographic areas to estimate consumer spending in its home appliances department.

It is estimated that these customers are a good sample of the 10,000 customers the store serves. The number of customers in each area is C 1  1,500, C 2  2,500, C 3  1,000, C 4  3,000, and C 5  2,000. It is found that the two consumers have the following budgets in dollars for home appliances per year: B 11  100, B 12  150; B 21  75, B 22  100; B 31  125, B 32  125; B 41  100, B 42  120;

and B 51  120, B 52  125.