Can someone help? I don’t get this

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?

Which of the following is the graph of y= square root -x-3

Which of these would have been most likely to have been a carpetbagger during the reconstruction era? a) a new york businessman who relocated to mississippi b) a former slave who was able to buy land in birmingham c) a carolina-born politician who supported the democratic d) a former confederate officer who owned a farm in memphis eliminate