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        riddles >> medium >> WHERE'S THE FATHER?
        
(Message started by: jeremiahsmith on Jul 28^th, 2002, 1:43am)

Title: WHERE'S THE FATHER?
Post by jeremiahsmith on Jul 28^th, 2002, 1:43am

The mother is 21 years older than the child. In 6 years from now, the mother will be 5 times as old as the child. Question: Where's the father?

All right... we can boil this down into two equations.

m = 21 + c
m + 6 = 5(c + 6)

where m and c are the ages of the mother and child.

Substitute 21 + c for m in the second equation...
21 + c + 6 = 5(c + 6)
27 + c = 5c + 30
0 = 4c + 3
-3 = 4c
-3/4 = c

So, the child is -3/4 years old. In other words, it's 9 months before it's born.

Soo...the answer? Assuming that the human gestation period is exactly 9 months, well, then, the father is currently having sex with the mother.

Title: Re: WHERE'S THE FATHER?
Post by Gareth Pearce on Jul 28^th, 2002, 6:27pm

Actually, since the child exists, implied by the statement that the mother is 21 years older ...
hes more likely to be asleep... (given the mother is 20 and 3 months, probable likelihood suggests he hasnt just walked out the door instead... maybe)

Title: Re: WHERE'S THE FATHER?
Post by Darin Seidel on Jul 29^th, 2002, 6:49am

Unless you assume that the mother was artificially inseminated, in which case the father could be anywhere ;D

Title: Re: WHERE'S THE FATHER?
Post by Court Jester on Aug 1^st, 2002, 3:15pm

jeremiahsmith's solution is sound enough and correct, think in terms of months instead of years and it all makes sense.

Title: Re: WHERE'S THE FATHER?
Post by Adhamhnon on Oct 7^th, 2002, 6:52pm

Actually, the riddle doesn't give the neccesary information to come to the conclusion... 21 and how many months older? If you do the math in a different way... you get..

21+6=27
27/5=5.4
12/10*4 (the decimal of the year) =4.8

So unless the baby is born exactly 4.2 months premature... the father is off drinkin with his buddies.
That is based on an exact 21 year difference in age.

Title: Re: WHERE'S THE FATHER?
Post by jeremiahsmith on Oct 8^th, 2002, 9:10am

on 10/07/02 at 18:52:49, Adhamhnon wrote:

Actually, the riddle doesn't give the neccesary information to come to the conclusion... 21 and how many months older?

21 years and zero months, apparently, because if the months had been important they would have been mentioned.

Quote:

If you do the math in a different way... you get...

...the wrong answer. It's simple algebra, here, folks.

Title: Re: WHERE'S THE FATHER?
Post by James Fingas on Oct 8^th, 2002, 9:42am

The important thing is that the human gestation period may be "9 months (plus one week)", but the start of those nine months is measured, not from the moment of conception, but from the start of the last menstrual period before conception. There are usually two weeks between these two events. Therefore, at this time it is one week before conception. There are, of course, many explanations:

a) The father is just ending his tour of duty, and will be back to his family in just a week.

b) The father is eyeing the mother in a bar.

c) The father is running around, preparing for his wedding in one week.

etc.

Title: Re: WHERE'S THE FATHER?
Post by jeremiahsmith on Oct 9^th, 2002, 10:27am

*sigh* Way to ruin a good math joke with details, guys. :D

Title: Re: WHERE'S THE FATHER?
Post by James Fingas on Oct 9^th, 2002, 11:42am

One could argue that a truly good math joke would be correct...

Title: Re: WHERE'S THE FATHER?
Post by Brian Lee on Nov 7^th, 2002, 1:20am

I'm new here...
Do you guys always beat everything to death like this?
:)

Title: Re: WHERE'S THE FATHER?
Post by jeremiahsmith on Nov 7^th, 2002, 4:55pm

Yes. As a matter of fact, oftentimes we don't stop when it's dead, and we continue beating it until it has been obliterated into its component particles. :D

Title: Re: WHERE'S THE FATHER?
Post by TimMann on Nov 7^th, 2002, 6:07pm

Then we take the particles, mold them into something that is almost but not quite entirely different from the original, and start beating on that. ;D

Title: Re: WHERE'S THE FATHER?
Post by Jeremy on Nov 8^th, 2002, 6:56am

and then we jump on them... and we continue to jump on them untill we can think of something more nasty to do.

Title: Re: WHERE'S THE FATHER?
Post by fenomas on Dec 16^th, 2002, 1:36am

I've been grasping with this, since a negative age is so unsatisfying. (Have you ever heard a pregnant mother say her baby is -2/9 years old?) It seems like there should be some possibilities based around the fact that, in common parlance, ages are always integral-- that is, someone who is 10 years and 2 months old is normally considered to have an age twice that of someone who is 5 years and 11 months. But I can't find any cool solutions making use of that. So I'm stuck with this:

One day about noon, a mother, aged 24, is sitting around with her daughter, age 3. They are talking about the how incredibly unlikely their situation is. The least of it is that they share a birthday, the mother having celebrated hers earlier that day, and the daughter due to be age 4 sometime that evening. Precisely 6 years later, they are once again discussing the amazing coincidence that the mother's age is now exactly 5 times the daughter's. Of course, this coincidence rather pales in comparison to the fact that both mother and daughter's birthday is February 29th, so the mother has seen only one birthday since their earlier conversation, and the daughter only two (making their ages now 25 and 5). (Mind you, the really amazing thing is that the daughter was born more than 80 years after the mother was!)

What do you think? Reaching? :)

Title: Re: WHERE'S THE FATHER?
Post by jeremiahsmith on Dec 16^th, 2002, 9:16am

Umm...people born on February 29th still get older in non-leap years, too...

Title: Re: WHERE'S THE FATHER?
Post by towr on Dec 16^th, 2002, 11:29am

but they don't have birthdays in non-leap years..

(everyone gets older in between birthdays too, but usually age is measured by birthdays)

Title: Re: WHERE'S THE FATHER?
Post by fenomas on Dec 16^th, 2002, 4:55pm

on 12/16/02 at 09:16:23, jeremiahsmith wrote:

Umm...people born on February 29th still get older in non-leap years, too...

Yeh, and unborn children don't have negative ages, other than by the sort of logic where you see one person go into a house and two come out, and deduce that the house has -1 people in it. So how about some slack? :/

Anyway, I never said the mother was "N years old", I said she was "aged N". So its a question of whether you define age in terms of years lived or birthdays seen. Given that my degree is in physics, it shouldn't surprise you that I chose the convention that would result in the answer I was looking for! :D

Title: Re: WHERE'S THE FATHER?
Post by Icarus on Dec 16^th, 2002, 5:58pm

Quote:

(everyone gets older in between birthdays too, but usually age is measured by birthdays)

I've known several people who were born on Feb 29, but none of them truly counted their age by birthdays! Age is traditionally truncated to the nearest year, or the nearest month for kids, but that is not the same as by birthday.

Quote:

Given that my degree is in physics, it shouldn't surprise you that I chose the convention that would result in the answer I was looking for!

Sorry, but a convention has to exist before you can choose it, and counting age by birthday is never done seriously. I have to agree with Jeremiah.

However, you could fix this by saying "On the mother's 24th birthday ...". Then this problem goes away.

Title: Re: WHERE'S THE FATHER?
Post by fenomas on Dec 16^th, 2002, 10:27pm

on 12/16/02 at 17:58:34, Icarus wrote:

No offense, me being a newbie and all, but if you're so enamored of following conventions literally, you might want to take another look at what I said about negative ages.

Anyway, if we're going to be technical, saying "on the mother's 24th birthday" doesn't really help my solution at all -- the problem specifically stipulates "the mother is 21 years older than the child". So my leap years idea doesn't fly, and even using integral ages goes against the way the problem is posed.

Wait a minute-- I've just shown an enormous flaw in my own idea... It's almost as if I knew the solution wasn't really literally valid when I made it!!! Bizarre... why would someone do such a thing?

Title: Re: WHERE'S THE FATHER?
Post by jeremiahsmith on Dec 17^th, 2002, 12:19am

Still, though, most people, after giving it some thought, would likely interpret a negative age as being before birth. It's not a normal convention by any means, I agree, but if you asked a bunch of people how old someone would be at negative 6 months, after a second or two, they'd likely say "Six months before they were born."

Or they'd just look at you funny.

Anyway, it's the only interpretation that would conceivably (ha ha pun) tell you where the father is :D

Title: Re: WHERE'S THE FATHER?
Post by fenomas on Dec 17^th, 2002, 1:19am

on 12/17/02 at 00:19:47, jeremiahsmith wrote:

Anyway, it's the only interpretation that would conceivably (ha ha pun) tell you where the father is :D

Oh contraire, Jeremiah, in my solution, the father is clearly in a grave, having died from the shock of conceiving a daughter with a woman born more than eighty years previous. :)

Jokes aside, I know all what you're saying- before I plugged in the numbers, I had a feeling that the answer was going to imply that the question takes place at the time of conception or of birth, for the sake of bringing the father into it. It's not as if the leap year thing was the first answer I arrived at! But after banging around looking for a clever answer that relies on integer math for ages and not finding one, I had an idea for a method that worked, but only if you accepted a patently incorrect (but sort of almost-logical) conception of "age". I thought such a solution was kind of funny-- mathematically consistent, yet painfully wrong. Thus my comment, "What do you think? Reaching?" Mind you, I'm all for being rigorous-- If you'd pointed out a problem with my math, I'd have been duly humbled. But if someone is going to pick at the logic underlying my (logically absurd) solution, naturally I must defend myself.

Possibly I'm being frivolous in a board where that's frowned on; I just arrived. If that's the case, then a big "my bad" out to everyone... m(_)m But surely its excusable if I was being frivolous in a mathematically correct way?