A friend sent me this:
14500 people are in a stadium, one of them gets called to come up on stage, what are the chances that that persons birthday lands on a sunday?
My guess is slighty over 1/52 but I’m not sure if my logic is completely wrong (theres slightly over 52 weeks in the year).
P.S. I tried google but came up with diddly squat for an answer.
So what are the chances and more importantly how did you figure it out?
For a given year, assuming birthdays are uniformly distributed, ~1/7th. Sunday is 1 of 7 days of the week.
Approximately 1/7th. It depends on the year. Some years have more Sundays than others.
Or, by “birthday,” do you mean the one day when someone was born?
The day of the week that a person’s birthday lands on changes every year.
I assumed it meant for that year. Maybe it was supposed to be a trick question.
I don’t think it means that year escpecially because no year was given. I also don’t think it is a trick question because I’m 99.99% positive there is some statistical formula for figuring out the answer . . . I just don’t know it.
I don’t know maybe there is some sort of catch in how you read it, but I don’t think so.
I would say 1/7. It doesn’t matter how many people are in the stadium. And it’s not exactly 1/7th unless there are an equal number of each day of the week in the year.
I’m sorry but I don’t think 1/7 is right, I don’t think my answer is right either but 1/7 just seems way to high, please explain your* logic.
1/7 would be the week but there are 52 weeks in the year, so it would be 1/7 of 1/52 which would be 1/364 which seems even more wrong. 
Edit* by your I mean the people who guessed 1/7th.
One in seven because there are seven days in the week. The question doesn’t specify a week of the year, so the fact that there are 52 weeks (or so) in a year doesn’t concern us.
And the rest of the question is unnecessary information to make you think you’re not doing something right.
Any random person’s birthday will be on any of the 7 days of the week. Therefore, there is a 1/7 chance that it will be on a sunday, assuming there is an equal number of each day of the week in the year. There probably isn’t, so it will be slightly higher or lower then 1/7th.
So I was overanalyzing the question . . . figures.
Oh well thanks for the help.
It’s a 100% chance that their birthday will be on a Sunday.
Since that day changes every year, it will eventually be on a Sunday.
Unless they’re really young and die before the time comes?
My b’day sits on a Sunday this year and so does my Italian mate. 
Simple: Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday: there are seven days on which you might have your next birthday (or your last birthday, or any birthday for that matter, now, in the past, or in a future year). Even leap year 2008 will not affect it. Your birthday, or anyone else’s birthday will fall on one of these. Therefore as many have pointed out, it is 1 chance in 7 of being Sunday. 1/7th.
Or 6 to 1 against.
The number of Sundays as opposed to Monday etc, in the year is irrelevant: the people in the stadium were not born this year. It would have been relevant if the question was "What are the chances of a baby being born on a Sunday this year.
Apologies in advance for this, and sorry to be blunt but what is far more difficult to understand is exactly why a 17 year old cannot figure this out for himself, without resorting to google and a unicycling forum. Why is he unable to sort the wheat from the chavs in this question? Anyone else find that depressing?
And where did the question come from? Is that a stock exam or homework question? For a 17 year old?
If this is the future for education levels in mathematics, what chance has MacDonalds got? How will they find anyone who can add on the cost of fries?
However, should you wish to complicate matters a little more, then it is in reality probably not 1 in 7. Other factors push their noses in. There is likely to be more sexual activity at the weekend, when the combatants are not too tired from the week’s work, when they have drunk more, and are more likely to forget their pill… add 9 months to that, seek out the relevant data, and you then might have an interesting statistical problem. 
Nao
Finally a voice of reason on this depressing thread! In return for such a fine post, I am more than willing to overlook a minor typo. I’m sure McDonald’s will be too. 
0.1415285714286
Ignoring that there are probably more C-sections done on weekdays
But yes this thread is depressing
I thought this was going to be the old classic, what are the chance two of them have the same birthday? as the answer is highly unintuitive for the uninitiated and therefore a good exam question. I seem to remember if you have 25 people in a room chances are two have the same birthday. But no, it’s 1/7, and yes that’s a worrying question for someone who would be doing their A-levels in the Uk.
Thank you. My youth has been poorly spent. I have need to revise my diet to include more of this undoubtedly fine food. My education depends upon it.
P.S. Poor attention to detail Miss A. I also missed off a quotation mark and a question mark.
Nao
I’m more interested in why they are being called up to the stage.
That’s too big a crowd for a magic show.
Wait, is it Courtney Cox at a Bruce Springsteen gig?
I don’t think it’s exactly 9 months, is it? It’s more like 9months ± a few days. Otherwise they’d always know exactly when to expect the baby to pop out and wouldn’t need to rush the mother to the hospital, right? So, that render the average sexual activity patterns pretty irrelevant.
Personally, I find it really depressing that a middle-aged person thinks that pregnant woman is like a ticking time-bomb that “goes off” on the exact set time. 
