A process with a mean output of 16 and a standard deviation of output of 0.75 has been provided specification limits of 19 and 13. What is the Cpk value of this process?
A) 0.33
B) 1.33
C) 1.00
D) Not enough information to answer this question

Question

Quizplus · Accepted Answer

Cpk is a measure of process capability that compares the distance between the process mean and the specification limits with the amount of variation in the process.

Cpk can be calculated using the formula:

Cpk = min((USL - mean)/3sigma, (mean - LSL)/3sigma)

Where: 
USL = Upper specification limit 
LSL = Lower specification limit 
mean = Process mean 
sigma = Standard deviation of the process

In this case, the process mean is 16, the standard deviation is 0.75, the USL is 19, and the LSL is 13. Plugging these values into the formula for Cpk gives:

Cpk = min((19 - 16)/(3 * 0.75), (16 - 13)/(3 * 0.75)) 
Cpk = min(1, 1) 
Cpk = 1

Therefore, the Cpk value of this process is 1, which is best represented by choice letter B.

A Process with a Mean Output of 16 and a Standard