One of Kraft's most popular cheese products is the "Singles American Slices". The mean weight of each cheese slice is 22 grams and standard deviation is 1.5 grams. One package contains 36 cheese slices and any package with an average weight per slice lower than 21.5 grams will be rejected.

Part A: What fraction of packages will be rejected because the average weight is too low?

Part B: In addition to original rejection criteria, suppose any packages that have an average weight per slice higher than 22.5 grams must be rejected as well. What is the total fraction of packages that will be accepted?