What is the probability that out of a group of 2 people, both will have same birthday. Assuming that there are 365 days and none have their birthday on 29th February.

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anonymous · Answer

@Astrophysics could you please help?

anonymous · Answer

You can use binomial expansion.
n=365
p=1/365 (probability of success of a trial)
q=1-p=1-1/365=364/365 (probability of failure of a trial)
The original formula is given by$$\left( nCx \right) *p ^{x}*q ^{n-x}$$
Where x is the number of desired successful trials.
Probability will than be P(X=2)$$(365C2)*(\frac{ 1 }{ 365 })^{2}*(\frac{ 364 }{ 365 })^{365-2}=0.184$$

anonymous · Answer

@Astrophysics