Machine Oil Is Used by Clothing Manufacturers to Lubricate and Protect

Multiple Choice

Machine oil is used by clothing manufacturers to lubricate and protect sewing machines. A company that produces machine oil must ensure that the viscosity of its product meets customer requirements. Consequently, the viscosity of every batch of oil produced is measured. Suppose that the process mean is 101 cP and the process standard deviation is 1.50 cP. What is the Cpk index if the customer specifications require viscosity of the machine oil to be 100 cP ± 4.5 cP?

A) 1.0
B) 1.22
C) 0.78
D) 1.67
E) 1.28