By design, a required dimension on a part is 0.575 cm plus or minus 0.008 cm. Assume that the process producing this part is stable with a mean of 0.579 cm and standard deviation of 0.002 cm. What is the Cp index?
A) 1.33
B) 2.00
C) 0.67
D) 1.00
E) 0.33

Question

Quizplus · Accepted Answer

The Cp index is calculated using the formula Cp = (USL - LSL) / (6σ), where USL is the upper specification limit, LSL is the lower specification limit, and σ is the standard deviation. Here, USL = 0.575 + 0.008 = 0.583 cm, LSL = 0.575 - 0.008 = 0.567 cm, and σ = 0.002 cm. Thus, Cp = (0.583 - 0.567) / (6*0.002) = 0.016 / 0.012 = 1.33.

By Design, a Required Dimension on a Part Is 0