🚀 go-pugleaf

Marie M. Moltubakk wrote:
> 
> I'm not sure this is the right place to ask, but I will try anyways. I
> attend an upper secondary school, and my teacher has just given us this:
> 
> Someone has a bath tub, and it is to be filled with water. If you tap cold
> water, it takes 9 minutes to fill it. If you tap warm water, it takes 12
> minutes. How much time will it take if you use both warm and cold water?
> 
> In my opinion there are more than one solution to this, because it depends
> on the bath tub. (Are there one or two taps, does the water run in the same
> speed or twice as fast when both warm and cold water is on?)
> 
> I have found one solution yet (two taps, double speed):
> 
> I set the size of the bath tub to 300 liters.
> Cold water: 33,33 liters/minute
> Warm water: 25 liters/minute
> 
> 33,33x+25x=300
> x=5,14
> 
> So, it would take 5 minutes and 8 seconds to fill the bath tub. Is this
> right, and what are the other ways to do it? This is probably easy for you
> skilled people, but not for me... Thanks in advance!
> 
> --
> ~Mmm
> *http://privat.riksnett.no/~arve.moltubakk/mmm/*

This is a clone of the "two guys are painting a room..." problem.
The "fast" trick is to take the product of the rates /sum of the rates.

I had a Student in College  Intermediate Algebra ( for about five days)
who had got the impression that EVERY problem involving two different 
numbers could be worked this way.
Ah..New MAth!!!