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  1. B

    Probability - Coin Toss - Find Formula

    Homework Statement Suppose a fair coin is tossed n times. Find simple formulae in terms of n and k for a) P(k-1 heads |k-1 or k heads) b) P(k heads | k-1 or k heads) Homework Equations P(k heads in n fair tosses)=binomial(n,k)/2^n (0<=k<=n) The Attempt at a Solution I'm stuck...
  2. B

    Probability. You roll, I roll game.

    Homework Statement You roll a die, and I roll a die. You win if the number showing on your die is strictly greater than the one on mine. If we play this game five times, what is the chance that you win at least four times? The answer is .1005 [b]2. Related Equations[\b] Binomial The Attempt...
  3. B

    Basic Probability Question—Rolling Die

    Basic Probability Question—Rolling Die!!! Homework Statement Suppose you roll a fair six-sided die repeatedly until the first time you roll a number that you have rolled before. A) for each r=1,2,... calculate the probability pr that you roll exactly r times. Homework Equations...