The following data have been collected by an accountant who is performing an audit of account balances for a major city billing department. The population from which the data were collected is the accounts for which the customer had indicated the balance was incorrect.

The dependent variable, y, is the actual account balance as verified by the accountant. The independent variable, x, is the computer account balance.

y 233 10 24 56 78 102 90 200 344 120 18 x 245 12 22 56 90 103 85 190 320 120 23

a. Compute the least squares regression equation.

b. If the computer account balance was 100, what would you expect to be the actual account balance as verified by the accountant?

c. The computer balance for Timothy Jones is listed as 100 in the computer account record. Provide a 90%
interval estimate for Mr. Jones’s actual account balance.

d. Provide a 90% interval estimate for the average of all customers’ actual account balances in which a computer account balance is the same as that of Mr. Jones (part c). Interpret.