I need help with math can anybody help

Ijust need to see how to do this. so you don’t have to answer all of them just a step by step explanation of one.

Calculate the missing value. round the answer to on decimal place. start with 70, increase it by 21%, and end up with

Using pert, adam munson was able to determine that the expected project completion time for the construction of a pleasure yacht is 21 months, and the project variance is 4. a) what is the probability that the project will be completed in 17 months? b) what is the probability that the project will be completed in 20 months? c) what is the probability that the project will be completed in 23 months? d) what is the probability that the project will be completed in 25 months? e) what is the due date that yields a 95% chance of completion?