Here's the bet: Flip the pennies and if they all come up the same--all heads or all tails--then you win a dime. Any other combination, you lose a nickel. See, at least two of the three pennies are going to match every time, so on the third coin you got a 50% chance, right? Easy money! Hint: The likelihood of a series of outcomes (all heads) is equal to the likelihood of the first outcome, times the likelihood of the second, times the likelihood of the third, and so on.  The Answer