The mass of a grain of rice is about 10^-4 ounces. About how many grains of rice are in a 10 pound bag?

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

Could somebody me with this radical simplification?

The difference of three and the reciprocal of a number is equal to the quotient of 20 and the number. find the number.