Aball is thrown in the air from a ledge. it's height in feet represented by f(x)=16(x^2-6x-7), where x is the number of seconds since the ball has been thrown. the height of the ball is 0 feet when it hits the ground. how many seconds does it take the ball to reach the ground?

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