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Re: Probability-A fair coin is flipped 5 times [#permalink]
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Solution


One solution can be simple manual combination techniques. As already discussed there can be \(2^5\) or 32 possible outcomes. The following cases are the relevant ones where the number of heads is more than tails:
  • 3 Heads 2 Tails: Total number of occurences is \((5!)/(3!)(2!)\) = 10
  • 4 Heads 1 Tail : Total number of occurences is \((5!)/(4!)(1!)\) = 5
  • 5 head 0 Tail : Total number of occurences is \((5!)/(5!)\) = 1

If you add the above occurrences it adds upto 16. So the probability is 16/32 or 1/2.
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Re: Probability-A fair coin is flipped 5 times [#permalink]
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soumya1989 wrote:

Solution


One solution can be simple manual combination techniques. As already discussed there can be \(2^5\) or 32 possible outcomes. The following cases are the relevant ones where the number of heads is more than tails:
  • 3 Heads 2 Tails: Total number of occurences is \((5!)/(3!)(2!)\) = 10
  • 4 Heads 1 Tail : Total number of occurences is \((5!)/(4!)(1!)\) = 5
  • 5 head 0 Tail : Total number of occurences is \((5!)/(5!)\) = 1

If you add the above occurrences it adds upto 16. So the probability is 16/32 or 1/2.



Plz clarify does it have the same meaning if the ques ask-

Probability of getting more heads than tails or the probability of getting at least 3 heads??
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Re: Probability-A fair coin is flipped 5 times [#permalink]
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pranab01 wrote:

Plz clarify does it have the same meaning if the ques ask-

Probability of getting more heads than tails or the probability of getting at least 3 heads??


Yes it is!
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Re: Probability-A fair coin is flipped 5 times [#permalink]
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Probability of getting 3 heads = 1/2 * 1/2 * 1/2 *1 * 1 = 1/8
Probability of getting 4 heads = 1/2 * 1/2 * 1/2 *1/2 * 1 = 1/16
Probability of getting 5 heads = 1/2 * 1/2 * 1/2 *1/2 * 1/2 = 1/32

The probability of getting 3 or 4 or 5 heads = 1/8+1/16+1/32 = 7/32
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Re: Probability-A fair coin is flipped 5 times [#permalink]
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Re: Probability-A fair coin is flipped 5 times [#permalink]
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