Question

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.

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