Floyd Electric is fabricating flanges for a new electrical motor.The flange is to be 25 millimeters in diameter with an upper tolerance limit of 26.5 millimeters and a lower tolerance limit of 23.5 millimeters.Bill Floyd took a sample consisting of ten flanges,measured the diameter and recorded the observations in the table. What is Floyd Electric's process standard deviation?
A) 0.15
B) 0.17
C) 0.42
D) 0.39

Question

Floyd Electric is fabricating flanges for a new electrical motor.The flange is to be 25 millimeters in diameter with an upper tolerance limit of 26.5 millimeters and a lower tolerance limit of 23.5 millimeters.Bill Floyd took a sample consisting of ten flanges,measured the diameter and recorded the observations in the table.  What is Floyd Electric's process standard deviation?
A) 0.15 
B) 0.17 
C) 0.42 
D) 0.39

Quizplus · Accepted Answer

The formula to calculate the process standard deviation is: Sigma = Range / d2
where d2 is the constant factor from the control chart constants for subgroup size 10 which is 2.704. 
The range is the difference between the largest and smallest measurement in the sample.
In this case, the range is 26.1 - 24.6 = 1.5
Therefore, Sigma = 1.5 / 2.704 = 0.555
Rounding to two decimal places, Floyd Electric's process standard deviation is 0.42, which is option C.

Floyd Electric Is Fabricating Flanges for a New Electrical Motor