There are 156 pupils in year 8.if 72 of them are girls how many are boys ?

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?

About 9% of th population is hopelessly romantic. if 2 people are randomly selected from the population, what is the probability that at least 1 person is hopelessly romantic?

Math i have no idea how to do a and b