PLEASE HELP:,) (plato)

Which is equivalent to 10/12? options: 10/18 5/6 3/12 9/11

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 standard deviation for a set of data is 5.5. the mean is 265. what is the margin of error?