Geeta and Seeta are friends. What is probability that both will have -
i) different birthday
ii) the same birthday (ignoring a leap year)
Let A denote the event that Geeta and Seeta have the same birthday.
and
denote the event that Geeta and Seeta have different birthday.
If Geeta and Seeta have the same birthday,
then their birthday could be on any one of the days from 365 days of the year.
∴ Number of cases in favourable of event A = 1
Required probability, P(A) =
As, we know that,
P(A) + P( ) = 1
Probability that Geeta and Seeta have the same birthday =
Probability that Geeta and Seeta have different birthday =