An object is dropped from a height of 100m, how long is it in the air?

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

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?

The distance of a chord from the centre of a circle is 12cm and the lenght of the chord is 10cm. find the radius of the circle