Chapter 19, Problem 21SE

An insurance company samples claim forms for errors created by its employees as well as the amount of time it takes to process a claim.

1. a. When the process is in control, the proportion of claims with an error is .033. A p chart has LCL = 0 and UCL = .068. Plot the following seven sample results: .035, .062, .055, .049, .058, .066, and .055. Comment on whether there might be concern about the quality of the process.
2. b. An $\bar{x}$ chart for the mean processing time has LCL = 22.2 and UCL = 24.5. The mean is μ = 23.35 when the claim process is in control. Plot the following seven sample results: 22.4, 22.6, 22.65, 23.2, 23.4, 23.85, and 24.1. Comment on whether there might be concern about the quality of the process.