The distribution of the length of bolts has a bell shape with a mean of 4 inches

Question:

The of the length of bolts has a bell shape with a mean of 4 inches and a standard deviation of 0.007 inch.
(a) About 68% of bolts manufactured will be between what lengths?
(b) What percentage of bolts will be between 3.986 inches and 4.014 inches?
(c) If the company discards any bolts less than 3.986 inches or greater than 4.014 inches, what percentage of bolts manufactured will be discarded?
(d) What percentage of bolts manufactured will be between 4.007 inches and 4.021 inches?
Distribution
The word "distribution" has several meanings in the financial world, most of them pertaining to the payment of assets from a fund, account, or individual security to an investor or beneficiary. Retirement account distributions are among the most...