if mean is 15.000 and we reject anything over 2 standard deviations away, we reject anything over 15.06 and under 14.94
go to
http://davidmlane.com/hyperstat/z_table.html
(the best stats page on the net)
enter 15 for the mean
enter .03 for SD
click on between and enter
14.94 and 15.06 and click "calculate" to get .0455
.0455(15000) = 682.5
The closest choice is B) 680
You are probably using "tables" or charts from a text book. This webpage is more accurate.
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
I think its A
1 answer