Alex flips a fair coin 20 times. Bert spins a fair coin 21 times. Bert wins if he gets more heads than Alex, else Alex wins. Note that Alex wins if there is a tie. What is the probability that Bert wins?

(In reply to flip vs spin by Jer)

It is almost certain

This assumption is based on one fact: the force with which the coin is spun. Unless Bert can somehow spin a coin with exactly the same force every time (extremely unlikely) and with the same orientation at the same spot on the surface he's spinning it on(also extremely unlikely, unless Bert is so inclined as to line up a coin before spinning, and one would have to hope for his sake that he isn't), and with the same position and movement of air particles (so hideously, remotely unlikely that its not even worth considering), then the outcome of the flip is going to be equally likely to be heads or tails.

Wow, I kept that sentence going.

Posted by Iain on 2004-05-20 17:12:04