Calling all statisticians:
You're in a packed bar, full of couples. What's the chance, under normal circumstances, of finding a couple who are both born in the same month?
I reckon it's one in twelve, but am I right?
After all, there are 144 different combinations, 12 of which are matches (Jan-Jan, Feb-Feb and so on). All the other combinations are duplicated once, (ie Jan-Dec, Dec-Jan), but I don't think that matters.
But I think I may have got it wrong. So, dear readers... to the rescue!
Posted by Eurodan at March 13, 2004 9:22 PMDefine your question better.
Is it: "You meet a couple. What's the chance, they' re both born in the same month?"
Then it's one in 12 (roughly, assuming months with identical length).
Is it: "You are in a bar. What is that chance that in this bar, there's a couple present with both partners born in the same month?". Then the probability is: 1 - (11/12)power N
Where N is the number of couples present in the bar.
And off course my bfr thinks I've made a fool of myself again.
If we assume that births are equally distributed throughout the year, that month of birth does not affect the way couples form, that the sample in your bar is representative of the population as a whole (a highly dubious supposition ;-) and ignore the fact that months vary in length between 28 and 31 days then I'd be inclined to agree that the probability of a randomly chosen couple having the same month of birth is indeed 1/12.
Posted by: Shyboy at March 13, 2004 11:23 PMThat'll teach me not to start a reply, come back to it after eating and not check to see if anyone else has responded in the meantime...
Posted by: Shyboy at March 13, 2004 11:27 PMAnd I had the same thought about the meaning of the question, and concur with the answer to the second interretation :-)
Posted by: Shyboy at March 13, 2004 11:36 PMI *am* having a bad day. That should read "interpretation". I don't want to send non-native English speakers scurrying for their dictionaries ;-)
Posted by: Shyboy at March 13, 2004 11:39 PMWell thanks very much Pascal and Adam (Adam, I knew you wouldn't be able to resist!).
And Pascal... welcome to my website - how did you find it?
Posted by: Eurodan at March 13, 2004 11:40 PMThis is completely off-topic and you most likely will be too busy to see it beforehand anyway, but I'd just like to wish you good luck for your test tomorrow. Knock 'em dead!
Posted by: matt at March 15, 2004 4:02 PMThank you very much indeed Matt... at the moment I'm in the 'calm before the storm' phase - feeling very zen about the whole thing. (But also very much hoping it goes well!)
I really appreciate the good wishes!
Dx
I'm this guy's http://www.hermanbeun.nl/ partner in crime and I tend to spy on him and his acquaintances via my rss aggregator http://www.bloglines.com :-)
Posted by: pascal van hecke at March 16, 2004 9:52 AMAha... that explains it...
Van harte welkom, trouwens ;-)
Posted by: Eurodan at March 16, 2004 10:56 PM