OT: Math problem... Options

[Jeroen]

Ok, here's a nice one...

A mother is 21 years older than her daughter.
In 6 years, this mother will be 5 times as old as her daughter

The question is: Where is the dad???

Intermezzo:
Some people get confused and will start asking WHO the dad is.
I don't know the question to that answer either. Only the mother can be 100% sure on that.
And no math can answer that questiong.

Some people may be confused by the sudden "appearance" of the dad and because of that, forget about the math.
Still, the question can be answered by simple math...

(scroll down for the solution)

































Set the mother's age to X
Set the daughter's age to Y

"The mother is 21 years older than her daughter" will then give this equation:
X = Y + 21

and "in 6 years, the mother will be 5 times as old as her daughter" will make:
X + 6 = 5(Y + 6)

We now have 2 equations with 2 unknowns, so we should be able to solve it:

In the second equation, substitute the value of X (= Y+21).
This will give:

Y + 21 + 6 = 5(Y + 6)
=>
Y + 27 = 5Y + 30
=>
Y - 5Y = 30 - 27
=>
-4Y = 3
=>
4Y = -3
=>
Y = 0.75

And there's the answer...!

The daughther is at this moment -0.75 years old, or -9 months
So the dad is on top of the mother right know (IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif)

[Aaron Cox]

QUOTE (Special_K @ Feb 1 2005, 12:15 AM)

Okay, Always old, sometimes new Never sad, sometimes blue Never empty, sometimes full Never pushes, always pulls What is it? I know, not a math question but..... (IMG:http://www.914world.com/bbs2/html/emoticons/bootyshake.gif)

dude- whats the answer?