Write 8.27 correct to 1 decimal place

Iam so stuck. what is the worked out answer for this question?

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

Hiroaki wants to find 3 3/4 - 7/8 explain why he must rename 3 3/4 to do the subtraction.