11) The project completion time of a project follows normal distribution. If the estimated time along the critical path is 260 days (mean project competition time) and the variance in the project completion time is 81, then a) What is the probability that the project will take 280 days or more to complete? b) What is the probability that the project will take between 240 and 280 days? c) What is the probability that the project will take 250 days or less to complete?