SOLUTION: Dave stands on a street corner tossing a coin. He decides to toss the coin 10 times, walking 1 block north if heads and 1 block south if tails. Find the probability he ends up 4 bl

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Question 237660: Dave stands on a street corner tossing a coin. He decides to toss the coin 10 times, walking 1 block north if heads and 1 block south if tails. Find the probability he ends up 4 blocks south of his original corner?
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
Dave stands on a street corner tossing a coin. He decides to toss the coin 10 times, walking 1 block north if heads and 1 block south if tails. Find the probability he ends up 4 blocks south of his original corner?
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The basic pattern is NNNSSSSSSS to get you to the 4 south end point.
But those 3 "N" moves can occur in 10C3 = 120 ways.
Each of those 120 patterns has probability (1/2)^10 = 1/1024
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Final Answer: 10C3*(1024) = 120/1024 = 0.117
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Cheers,
Stan H.