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)

[SpecialK]

Old mathimeticians never die, they just lose some of their functions..... (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)


Three men were on a business trip and had to stay in a hotel
over night. The price of the room was $30.00, so the men
decided to split one room, three ways. Each one paid $10.00.
Well after they paid, the manager realized that he overcharged
them on their room. The room only cost $25.00, so he gave the
bellboy five one dollar bills to give to the three men. On his
way up to the room the bell boy was trying to think of a way to
split $5.00 three ways. After thinking about it awhile, he decided
to keep $2.00 for himself and give each man $1.00 back. Now, if
each man (who paid $10) gets $1 back that means they each paid
$9.00 ($10 - $1 = $9 ). $9.00 multiplied by 3 (because there are
three men) equals $27.00 plus the $2.00 the bell boy kept equals
$29.00! What happened to the missing dollar?????


Old one....but makes you go hmmmm. (IMG:http://www.914world.com/bbs2/html/emoticons/huh.gif)