An x chart is used to maintain current control of a process. The cost parameters are a1 = $2, a2 = $0.50, a3 = $50, a′3 = $75, and a4 = $200. A single assignable cause of magnitude δ = 1 occurs, and the duration of the process in control is an exponential random variable with mean 100 h. Sampling and testing require 0.05 h, and it takes 1 h to locate the assignable cause.