What is the probability that, of three people selected at random, at least two were

born on the same day of the week?

I know the answer is 19/49 but how?

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- April 16th 2011, 11:34 AMsundance240Probability that of 3 people selected at random, at least 2 were born on the same day
What is the probability that, of three people selected at random, at least two were

born on the same day of the week?

I know the answer is 19/49 but how? - April 16th 2011, 11:45 AMPlato
- April 16th 2011, 11:45 AMyyhow
Chance of at least two were born on the same day of the week = 1 - Chance of all three born on different days of the week

Chance of three random people born on different days of the week = 1 * 6/7 * 5/7 = 30/49

Chance of at least two were born on the same day of the week = 1 - 30/49 = 19/49

Sorry for re-post, didn't see the above reply - April 17th 2011, 10:56 AMSherrie
I believe this is also called the birthday paradox. Birthday problem - Wikipedia, the free encyclopedia