Would you me to solve this 9.1x10^-5)^-4

Carl's candies has determined that a candy bar measuring 3 inches long has a z-score of +1 and a candy bar measuring 3.75 inches long has a z-score of +2. what is the standard deviation of the length of candy bars produced at carl's candies?

What is the product? a-3/15a × 5/a-3

On the first of each month sasha runs a 5k race she keeps track of her times to track her progress her time in minutes is recorded in the table