## whatu Group Title Find the chance that the 5 people have 5 different birthdays. Here is my workings but I think I have gone wrong somewhere 364/365*364/365*363/365*362/365*361/365= I can't seem to get it right have I calculated something wrong? one year ago one year ago

1. Jack1 Group Title

= 1 - probability that 2 people have the same birthday

2. Jack1 Group Title

sorry, rephrase: = 1-[(probability that any 2 people have the same birthday)+(probability that any 3 people have the same birthday)+(probability that any 4 people have the same birthday)+(probability that any 5 people have the same birthday)

3. whatu Group Title

it is a bit like that but I am looking at five people with five different birthdays. I just want to know I am on the right track.

4. Jack1 Group Title

not great with probability sorry, will get: @Mertsj @amistre64 @hartnn @Callisto @mathslover these guys are the beez neez

5. Jack1 Group Title

maybe they're not on right now, will try: @UnkleRhaukus and @hba pretty please?

6. Jack1 Group Title

was thinking now that the answer is 1-probability that 5 people have the same birthday...?

7. whatu Group Title

ok think I have worked it i.e. -1 1 person 365 2 364 3 363 4 362 and 5 361 do we mutiple all these with 365 days excluding a leap year? that is five people with five diffrent birthdays

8. Jack1 Group Title

ideas @hba ??

9. amistre64 Group Title

my idea is, and it could be faulty ...... $\binom{5}{5}\left(\frac{1}{365}\right)^{5}\left(\frac{364}{365}\right)^{0}$

10. amistre64 Group Title

ppppp ppppf pppfp ppfpp pfppp fpppp pppff ... i think the count for 5 people is 1+5+10+10+5+1 = 32 different scenarios

11. amistre64 Group Title

the probability that any given person has a birthday on a given day is 1/365, so the compliment of that is 364/365

12. amistre64 Group Title

...lol, never did like this particular one. satelitte has it tattoed someplace im sure

13. amistre64 Group Title

finding the chance that they have the same birthday might be easier; then its just 1-same birthdays