Please help me with my math homework question 4

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

The number of students who ride a school bus is 110% of the number of students who walk. how many students ride the school bus?

The town of springfield, usa has a population of 9900 people. the population is growing at a rate of 2.3% each year. which expression gives the town's population 5 years from now? choose 1