Question 2: 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, four units of output were sampled from each machine, with the following results:

Machine	Measurements
#1	17	15	15	17
#2	16	25	18	25
#3	23	24	23	22

1. Using the factors for three sigma control limits, what are the x-bar chart upper and lower control limits?