Question

It is given that in a group of 3 students, the probability of 2 students not having the same birthday is 0.992. What is the probability that the 2 students have the same birthday?

Answer 1

Probability that two students are not having same birthday P`(barE)` = 0.992

Probability that two students are having same birthday P (E) = 1 − P (`barE`)

= 1 − 0.992

= 0.008

Answer 2

Let the probability of 2 students having same birthday = P(SB)

And the probability of 2 students not having the same birthday = P (NSB)

∴ P(SB) + P (NSB) = 1

P (SB) + 0.992 = 1

P (SB) = 1 − 0.992

P (SB)= 0.008