question_answer 1)

A person buys is lottery ticket in 50 lotteries, in each of which his chance of winning a prize is  What is the probability that he will win a prize (z) at least once (b) exactly once (c) at least twice.  

Answer:

Let is the number of wins, then x has the nonimial distribution with n = 50, p =             (a) P(atleast once)         = 1 ? P(x<1) = 1 ? P(x = 0)             (b) P (exactly once) = P (x = 1)                     (c) P (atleast twice) = P(x  2) = 1 ? P(x < 2)       = 1 ? [P (x = 0) + P (x = 1)]