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The more complex stuff I get, why did I get stuck on this?

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by Rahul@gurome » Thu Dec 09, 2010 3:30 am
ithamarsorek wrote:When tossing a fair coin 4 times what is the likelihood of having at least 3 heads?
The event "at least 3 heads" contains the following events:
  • 1. Exactly 3 heads.
    2. Exactly 4 heads.
Possible exactly 3 heads: (HHHT), (HHTH), (HTHH) and (THHH)
Each have a probability 1/16 => Total = 4*(1/16) = 1/4

Possible exactly 4 heads: (HHHH) => Probability = 1/16

Required probability = (1/4) + (1/16) = 5/16
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