In a group of 4 people, what is the probability of finding 3 persons with the same month of birth?
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the "single" person could be any of 4 & have birthday in any month, so 48 ways
the "threesome" could have birthday in any of remaining months = 11 ways
total ways (each person has 12 choices) = 12^4
Pr = 48*11/12^4 = 11/432, ≈ 2.546% <---------
note:
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i have taken the q to mean "exactly 3" persons with the same month of birth
if "at least" 3 is to be taken, add 12/12^4 = 1/12^3 to the answer
the "threesome" could have birthday in any of remaining months = 11 ways
total ways (each person has 12 choices) = 12^4
Pr = 48*11/12^4 = 11/432, ≈ 2.546% <---------
note:
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i have taken the q to mean "exactly 3" persons with the same month of birth
if "at least" 3 is to be taken, add 12/12^4 = 1/12^3 to the answer
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i really dont feel like thinking to hard so i cant answer that but the other answer ( 75%) is just stupid. the answer will be a very low percentage.sorry i couldn't answer i just wanted to make sure you didint pick 75% which is stupid.
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75%