A manufacturer knows that on average 20% of the electric toasters produced require repairs within 1 year after they are sold. When 20 toasters are randomly selected, find appropriate numbers x and y such that

(a) the probability that at least x of them will require repairs is less than 0.5;

(b) the probability that at least y of them will not require repairs is greater than 0.8.

(a) the probability that at least x of them will require repairs is less than 0.5;

(b) the probability that at least y of them will not require repairs is greater than 0.8.