show work in excel please

Below are the optimistic (a), most likely (m) and pessimistic (b) times (in days) for the activities on the critical path for a large project. TASK m b A 4 15 17 00 7 12 21 C 3 ON 13 D 6 14 27 E 18 27 29 Copy data into Excel. 1. Find the project (critical path) expected time and standard deviation. 2. Find the probability of the project (critical path) being completed in 70 days. 3. How many days should be allocated to by 95% certain the project will be completed