Monday, September 8, 2008

If there are 23 people in a room, there's a 50% chance that two of them will share a birthday (it's been proven mathematically).

Today is JLW's birthday, too. He shares it with Chea.
Happy Birthday, GB. May the coming year find you less reliant on Tums:)

Doctor, I get heartburn every time I eat birthday cake." Next time, take off the candles."

Dana said...

Happy Birthday, Jantzen!

Kodison said...

I must say BelleMa, it's great to see you delving into the magical world of statistics... I can vouch for your claim regarding birthdays and the probability of several of them having the same birthday. Here's the equation for this particular problem:

The Probability that NO two people in a group have the same birthday is as follows:

365!/[(365-n)!365^n]
Where n= the number of people in the sample group.

For this example, when using n=23, our final answer is 0.4927, or as a percentage, 49.27%. This answer tells us that there is a 49.27% probability in a group of 23 people, that NO two people share a birthday. Therefore we can subtract our answer from 1 to get the answer we're looking for...

1-0.4927=0.5073

This tells us as you stated in your post, that in a group of 23 people, there is a 50.73% probability that at least two people share a birthday.

Considering that both Megs and I share the same birthday, using this same equation to determine the probability of any two people sharing the same birthday, we had a (1-0.9973=0.0027) or 0.27% probability of sharing a birthday.

Oh the magic of statistics.

ld said...

I usually defer to Dilbert's method of statistical analysis...much easier to compute.