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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?
Solution 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
Solution 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
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