Question

1. The diameter of a shaft is normally Gaussian distributed with a mean value of 0.2508 inches and a standard deviation of 0.0005 inches. The Upper and Lower control limits are specified as 0.25 + - 0.0015 inches.

a) What proportions of shaft do not conform to the specifications?

b) Please hand draw a picture of a normal Gaussian curve to show the proportions conforming and non-conforming.

Answer 1

X : diameter of a shaft

X ~ N ( 0.2508 , 0.0005)

the specification limits are :-

( 0.25-0.0015 , 0.25+0.0015) = (0.2485 , 0.2515)

a). the proportions of shaft that do not conform to the specifications are:-

[ using standard normal table]

b).the normal curve be:-

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