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Hi, if I run a draw each week where there are 10 prizes. There are 100 tickets in existence. The probability of winning a prize is therefore for 10/100. If I had 2 tickets the probability of winning in a week would be 2*10/100. If I look at this probability over a year (52 draws) or 2 years ( 104 draws)?.i start getting confused. The probability of this becomes greater than 1 using my logic. Any ideas on correct probabilities? I think i need to look at the binomial distribution.? Thanks in advance.

Two mistakes.With 2 tickets, the probability to win at least one price is 1-the probability to lose for your two tickets. Moreover, the probability for each ticket are not independant.So the probability is 1-90/100*89/99To look over one year, you can use the same formula but here the probability are independant:If p is the probability to win over one period, the probability to win over T period is 1- (1-p)^T <1