I need help ASP on this

Four airplanes carrying a total of 400 passengersarrive at the detroit airport. the airplanes carry, respectively,50, 80, 110, and 160 passengers. a) one of the 400 passengers is selected uniformly at random. let x denote the number of passengers that were on theairplane carrying the randomly selected passenger. find var(x)for x as given in the problemb) one of the 4 airplane drivers is also selected uniformly atrandom. let y denote the number of passengers on the chosen driver’s airplane. find var(y) for y as given in the problem

Use composition to determine if (x) or h(x) is the inverse of f(x) for the limited domain x2-1.

Ijust need these 2 questions answered (the second pic is just confirmation i'm not confident in that answer)