stat既問題!!!!!!!!急!!!!!!!

A machine used to fill cereal boxes dispenses on average m ounces per box. The manufacturer wants the actual ounces dispensed, X, to be within 1 ounce of m at least 75% of the time. What is the largest value of the standard deviation that can be tolerated if the manufacturer's objectives are to be met?

Suppose that we toss a fair coin until a head first comes up, and let X represent the number of tosses which were made. Then the possible values of X are 1, 2, . . ..
Is X a binomial or Poison random variable? Find the probability distribution function of X and the expected value of X.

In Las Vegas the roulette wheel has a 0 and a 00 and then the numbers 1 to 36 marked on equal slots; the wheel is spun and a ball stops randomly in one slot. When a player bets 1 dollar on a number, he receives 36 dollars if the ball stops on this number, for a net gain of 35 dollars; otherwise, he loses his dollar bet. Find the expected value for his winnings.