7. A Quality Analyst wants to construct a control chart for determining whether three machines, all producing the same product, are under control with regard to a particular quality variable. Accordingly, he sampled four units of output from each machine, with the following results: Machine Measurements #1 17, 15, 15, 17 #2 16, 25, 18, 25 #3 23, 24, 23, 22 For upper and lower control limits of 23.29 and 16.71, which machine(s), if any, appear(s) to have an out-of-control process mean? A) machine #1 B) machine #2 C) machine #3 D) All of the machines E) None of the machines