Question

 A manufacturer of bolts has a quality-control policy that requires it to destroy any bolts that are more than 4 standard deviations from the mean. The quality-control engineer knows that the bolts coming off the

 assembly line have mean length of 15 cm with a standard deviation of 0.05 cm. For what lengths will a bolt be destroyed?

 Select the correct choice below and fill in the answer box(es) to complete your choice.

 (Round to one decimal place as neoded.)

Answer 1

We have given mean = 15 and standard deviation = 0.05

And we have given that bolt is to destroy if it is more than 4 standard deviations from mean.

Hence

mean - 4 * standard deviation = 15 - 4 * 0.05 = 15 - 0.2 = 14.8

mean + 4 * standard deviation = 15 + 4 * 0.05 = 15 + 0.2 = 15.2

Hence B. A bolt will be destroyed if its length is less than 14.8 cm or greater than 15.2 cm is correct answer.

Hope this will help you. Thank you :)