A laser surgery process has tolerances of plus or minus .01 inches. What does the process standard deviation need to be in order for this process to have a capability ratio of 1.00?
A) 0.02 inches
B) 0.0033 inches
C) 0.002 inches
D) 0.033 inches

Question

Quizplus · Accepted Answer

The capability ratio is calculated by dividing the specification limit by the process standard deviation. In this case, the specification limit is 0.01 inches and the capability ratio is 1.00, so the process standard deviation must be equal to the specification limit. Therefore, the process standard deviation needs to be 0.01 inches. However, the answer choices are not in inches, so we need to convert: 
A) 0.02 inches = capability ratio of 0.5 
B) 0.0033 inches = capability ratio of 3.03 
C) 0.002 inches = capability ratio of 5 
D) 0.033 inches = capability ratio of 0.30 
Only option B has a capability ratio of 1.00, so the answer is B.

A Laser Surgery Process Has Tolerances of Plus or Minus