In a competitive exam 5 marks are awarded for every correct answer 2 marks are discued for every wrong answer and 0 marks are given for not answering a question .Find the source of a boy who attempt all question (20) but only 12 answer are correct

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?