Question

Design specifications require that a key dimension on a product measure 100 /- 10 units. A process being considered for producing this product has a standard deviation of four units. a. What can you say (quantitatively) regarding the process capability

Answer 1

0.8333

Explanation:

Given :

Mean, X = 100

Lower Specification Limit, LSL = 100 - 10 = 90

Upper Specification Limit, USL = 100 + 10 = 110

Standard Deviation, σ = 4

The process capability index, Cpk;

Cpk = Min[(X - LSL) / 3σ; (USL - X) /3σ]

Cpk = Min[(100 - 90) / 12 ; (110 - 100 ) /12]

Cpk = Min [0.8333 ; 0.8333]

Hence, Cpk = 0.8333