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?
A)3.33
B)1.67
C)0.83
D)2.50
E)none of the above

Question

Quizplus · Accepted Answer

Cpk is calculated as the minimum of (USL - Mean) / 3*Standard Deviation and (Mean - LSL) / 3*Standard Deviation. 
Here, USL = 10 cm and LSL = 8 cm. 
Cpk = min((10-9.5)/(3*0.2), (9.5-8)/(3*0.2)) = min(1.67, 0.83) = 0.83. 
Therefore, the process capability is 0.83, which is option C.

The Specification Limit for a Product Is 8 Cm and 10