posted by tara
suppose the replacement times for washing machines are normally distributed with mean 8.6 years and standard devistion of 1.6years.
a. what percentage of washing machines have replacement times less than 7 years?
b. find the probability that a washing machine will have a replacement time of more than 6.5 years?
Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to the Z scores.