Question

The specification limit for a product is 8 cm and 10 cm. A process that produces the product has a mean of 9.5 cm and a standard deviation of 0.2 cm. What is the process capability, Cpk, and is the process capable or not?

A. Cpk = 1.00, the process is not capable

B. Cpk = 1.67, the process is capable

C. Cpk = 0.83, the process is not capable

D. Cpk = 2.50, the process is capable

E. Cpk = 5.00, the process is capable

Answer 1

C. CpK = 0.83, the process is not capable

Step-by-step explanation:

CpK = Min(CpU, CpL)

CpU = (Upper Specific Limit - Mean)/3*Standard Deviation

= (10-9.5)/3*0.6

= 0.83

CpL = (Mean - Lower Specific Limit)/3*Standard Deviation

= (9.5-8)/3*0.2

= 2.5

CpK = Min(0.83,2.5)

= 0.83