Question

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.

Answer 1

@Astrophysics could you please help?

Answer 2

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)\[(365C2)*(\frac{ 1 }{ 365 })^{2}*(\frac{ 364 }{ 365 })^{365-2}=0.184\]

Answer 3

@Astrophysics