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Question: Answered & Verified by Expert
2n unbiased coins are tossed. The probability of having the number of heads is not equal to the number of tails is
MathematicsProbabilityTS EAMCETTS EAMCET 2020 (09 Sep Shift 1)
Options:
  • A 2n!n!2122n
  • B 1-2n!n!2
  • C 2n!n!2
  • D 1-2n!n!2·14n
Solution:
1170 Upvotes Verified Answer
The correct answer is: 1-2n!n!2·14n

Considering that a coin is tossed 2n times then we get a probability distribution

=122nc02n+c12n+c22n+...+cr2n+...+c2n2n

Pr=122ncr2n

So probability of getting the same number of heads as tails

=Pn=122n×cn2n

Req. Prob.=1-14ncn2n

=1-2n!n!2·14n

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