Chapter 6.1, Problem 13P

Control Charts: Bank Loans Tri-County Bank is a small independent bank in central Wyoming. This is a rural bank that makes loans on items as small as horses and pickup trucks to items as large as ranch land. Total monthly loan requests are used by bank officials as an indicator of economic business conditions in this rural community. The mean monthly loan request for the past several years has been 615.1 (in thousands of dollars) with a standard deviation of 11.2 (in thousands of dollars). The distribution of loan requests is approximately mound-shaped and symmetric.

1. (a) For 12 months, the following monthly loan requests (in thousands of dollars) were made to Tri-County Bank:

Make a control chart for the total monthly loan requests, and plot the preceding data on the control chart. Interpretation From the control chart, would you say the local business economy is heating up or cooling down? Explain your answer by referring to any trend you may see on the control chart. Identify all out-of-control signals by type (I, II, or III).

1. (b) For another 12-month period, the following monthly loan requests (in thousands of dollars) were made to Tri-County Bank:

Make a control chart for the total monthly loan requests, and plot the preceding data on the control chart. Interpretation From the control chart, would you say the local business economy is heating up, cooling down, or about normal? Explain your answer by referring to the control chart. Identify all out-of-control signals by type (I, II, or III).