Likelihood

• February 5th 2009, 03:02 AM
Shandy
Likelihood
Hi!

If there are 10 people in the same room and they were all born in the same year what would be the likelihood that at least two of them were born exactly the same day?

• February 5th 2009, 04:10 AM
Rincewind
Quote:

Originally Posted by Shandy
Hi!

If there are 10 people in the same room and they were all born in the same year what would be the likelihood that at least two of them were born exactly the same day?

The probability is 1 - the probability of them all being born on different days.

$p = 1 - \frac{365!}{365^{10}(365-10)!}$

$p = 1 - \frac{365\times 364\times 363\times 363 \ldots 356}{365^{10}}$

$p \approx 0.1169481777$
• February 5th 2009, 04:50 AM
mr fantastic
Quote:

Originally Posted by Shandy
Hi!

If there are 10 people in the same room and they were all born in the same year what would be the likelihood that at least two of them were born exactly the same day?