Question

A manufacturer of industrial solvent guarantees its customers that each drum of solvent they ship out contains at least 100 lbs of solvent. Suppose the amount of solvent in each drum is normally distributed with a mean of 101.8 pounds and a standard deviation of 3.76 pounds.

Required:
a. What is the probability that a drum meets the guarantee? Give your answer to four decimal places.
b. What would the standard deviation need to be so that the probability a drum meets the guarantee is 0.99?

Answer 1

The answer is "0.6368 and 0.773".

Explanation:

The manufacturer of organic compounds guarantees that its clients have at least 100 lbs. of solvent in every fluid drum they deliver.
`X\ is\ N(101.8, 3.76)\\\\P(X>100) =P(Z> (100-101.8)/(3.76)=P(Z>-0.47))`

For point a:

Therefore the Probability =0.6368

For point b:

`P(Z\geq (100-101.8)/(\sigma))=0.99\\\\P(Z\geq (-1.8)/(\sigma))=0.99\\\\1-P(Z< (-1.8)/(\sigma))=0.99\\\\P(Z< (-1.8)/(\sigma))=0.01\\\\z-value =0.01\\\\area=-2.33\\\\ (-1.8)/(\sigma)=-2.33\\\\ \sigma= (-1.8)/(-2.33)=0.773`