In article <148b5$47fc23bb$45283fd7$18621@[EMAIL PROTECTED]
>, Marvel
<goh@[EMAIL PROTECTED]
> wrote:
> "Paul Sperry" <plsperry@[EMAIL PROTECTED]
> wrote in message
> news:080420080115029670%plsperry@[EMAIL PROTECTED]
> > In article <42244$47fad5af$45283fd7$2586@[EMAIL PROTECTED]
>, Marvel
> > <goh@[EMAIL PROTECTED]
> wrote:
> >
> >> What would the formula be?
> >>
> >> In a bag of red and black marbles there are 18 fewer red marbles
than
> >> black
> >>
> >> If 45% of the marbles are red how many marbles are in the bag.
> >>
> >>
> >
> > The problem is about red and black marbles and asks a question about
> > "how many" so it seems a good start would be to let R be the number of
> > red marbles and B the number of black marbles.
> >
> > Now translate:
> >
> > "there are 18 fewer red marbles than black" i.e. R = B - 18.
> >
> > "45% of the marbles are red" A little trickier; 45% of _all_ the
> > marbles are red i.e. R = 0.45(R + B).
> >
> > So,
> >
> > R = B - 18 and
> > R = 0.45(R + B).
> >
> > Can you take it from there? If not, get back to us.
> >
> > --
> > Paul Sperry
> > Columbia, SC (USA)
> >
> I'm getting back because I don't get R = 0.45(R + B).
R + B is all the marbles 45% of which are red.
> Now I see 45% and 55% who have a difference of 10 and 18 is the 10.
>
> So eighteen is ten per cent of the entire thing, meaning one hundred
eighty
> is 100%
A more elementary i.e. better way than mine. In fact, you went straight
for the answer where I found R and B and added them. If T is the total
number of marbles, R = 0.45T and so B = 0.55T so 0.1T = B - R = 18.
> Marvel
> Charlotte N.C. USA
A virtual neighbor.
--
Paul Sperry
Columbia, SC (USA)
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