A betting company wishes to sell 5000 tickets 50 of which will win prizes. I.) A students decided to buy 200 tickets. Let X be the number of tickets that win a prize. Write the probability distribution of X and give its mean. Ii.) Using a Poisson approximation for the distribution of X find the probability of at least three tickets winning a prize. Iii.) Calculate the number of tickets that should be bought so as the probability of at least one winning a prize is 90%