For a specific type of machine part being produced, the diameter is normally distributed, with a mean of 15.000 cm and a standard deviation of 0.030 cm. Machine parts with a diameter more than 2 standard deviations away from the mean are rejected.

Question

If 15,000 machine parts are manufactured, how many of these will be rejected?

A)
560

B)
680

C)
750

D)
970

Answer 1

I think this site will be a big help.

http://davidmlane.com/hyperstat/z_table.html

It will show you the fraction more than 2 std away, and you can multiply that by 15000 to get your answer.

Answer 2

c.750