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?

The correct answer is 0.008

Let P(E) be the probability that the event E will happen.
∴ The probability of event E not happening can be written as 1 - P(E)
P(Ē) = 1 - P(E)
∴ In this case, probability that 2 students having the same birthday = 1 - probability of 2 students not having the same birthday.
P(Ē) = 1 - 0.992 = 0.008