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A Coin Game (Posted on 2004-05-20) Difficulty: 3 of 5
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?

See The Solution Submitted by Brian Smith    
Rating: 3.0000 (3 votes)

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Solution Assuming .5 solution | Comment 3 of 11 |

On my TI-83 calculator

sum(seq((binompdf(21,.5,x)*binomcdf(20,.5,x)),x,0,20)

gives .6223851943 (replace the first .5 with the appropriate probability if Bert really does get to spin.

So winning in a tie is better than getting an extra spin.

gotta like a 1 line solution

-Jer


  Posted by Jer on 2004-05-20 14:19:31
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