Math
posted by Nathan on .
The batteries from a certain manufacturer have a mean lifetime of
890
hours, with a standard deviation of
90
hours. Assuming that the lifetimes are normally distributed, complete the following statements.

What statements? You cannot copy and paste here.
Just guessing:
Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions/probabilities related to your Z scores.