The daily sales of a retail store are normally distributed with a standard deviation of $500. If the probability that sales will be less than $10,000 in any one day is 40%, what are the mean daily sales?

Answer 1

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion/probability (.40) and its Z score.

-Z = (score-mean)/SD = (10,000-mean)/500

Answer 2

$10,126.65