You walk into a room with 4 other people in it. What is the probability that one or more of them has a birthday in the same month as yours? Answer with a percen

Question

You walk into a room with 4 other people in it. What is the probability that one or more of them has a birthday in the same month as yours? Answer with a percentage rounded to the nearest tenth of a percen

Answer 1

Your birthday -- let's say November.

 

Other Person # 1  P(different birthday month) = 11/12

Same for O P # 2, 3 & 4.

 

P(all four Other Persons born not in your month) = (11/12)⁴

 

∴ P(at least one O P was born in your month) = 1 - the above quantity = 0.2939... or 29.4%