sandman wrote:

In a raffle in which 200 tickets are sold, there are 3 prizes - first prize of $100, second prize of $50, third prize of $30. A girl has one ticket in the raffle. What is the probability that she wins

(a) a prize,

(b) at least $50.

I really suck at Probaility and counting. But here's my try.

1) Atleast a prize:

P(First) = 1/200 (she has one ticket, hence the probability of her winning the prize is 1 in 200)

P (Second) = 199/200 * 1/199 (Probability of not winning first * Probability that she wins 2nd)

P(third) = 199 / 200 * 198/199 * 1/198 (Prob of not winnning first and second * prob of winning third)

P (at least one) = P(First) + P(second) + P(Third)

2) Winning 3rd - P(Third) from above.

Am I right?