100 people 365days, whats P(atleast two have birthday on the same day)
2007-05-06 21:50:55 · 6 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
well can anyone get me 100% correct answers. There are all different answers and i am confused
2007-05-06 22:49:21 · update #1
P(100 match) = 99.999969%
P(100 match) = 1 - P(100 no match)
= 1 - (365/365)(364/365)(363/365). .(266/365) = .99999969
= 99.999969%
Actually it only takes 23 people to have a better than 50% chance that two people will have a matching birthday. The reason for the surprisingly low number is that you are not specifying what two people will match or what day the matching birthday will be.
2007-05-06 22:01:50 · answer #1 · answered by Northstar 7 · 1⤊ 1⤋
The way to figure this is to work out the probability that no 2 people have the same birthday and subtract from 1:
1 - (364 * 363 * 362 * .... * 266 * 265)/365^99 = approaching 100%
2007-05-06 22:06:41 · answer #2 · answered by blighmaster 3 · 0⤊ 1⤋
For any particular date in the year, one person will have a 1/ 365 chance.
So for a hundred people, there will be one hundred chances.
1/ 365 * 100 = 100/ 365
1/ 365 * 100 = 0∙273 972 602
When you consider the first person and a date is picked, that only leaves 99 more chances.
1/ 365 * 100 - 1/ 365 =
0∙273 972 602 - 0∙00273 972 602 = 0∙271 232 876
Answer is : 0∙271 232 876
That is : 27∙1 % chance.
2007-05-06 22:20:00 · answer #3 · answered by Sparks 6 · 0⤊ 3⤋
Good question... fooled everyone.
The probability that each will have a different date is
(365! / 265!) / 365^100
The required answer therefore is 1 minus the above, that is
( 365^100 - 365! / 265! ) / 365^100
2007-05-06 22:09:57 · answer #4 · answered by small 7 · 1⤊ 2⤋
100/365 + 100/365 =200/365
2007-05-06 21:56:23 · answer #5 · answered by Anonymous · 0⤊ 4⤋
0.273972602739726027397. All you have to do is 100 divided by 365
2007-05-06 22:01:15 · answer #6 · answered by Anonymous · 0⤊ 4⤋