On Apr 13, 8:36=A0pm, "Brian M. Scott" <b.sc...@[EMAIL PROTECTED]
> wrote:
> On Sun, 13 Apr 2008 11:41:56 -0700 (PDT),
> <dzogche...@[EMAIL PROTECTED]
> wrote in
> <news:bfc67021-aa78-473a-ba08-44aabd8b7212@[EMAIL PROTECTED]
>
> in alt.math.undergrad:
>
> > On Apr 13, 5:25=A0pm, "Brian M. Scott" <b.sc...@[EMAIL PROTECTED]
> wrote:
> >> On Sun, 13 Apr 2008 08:03:41 -0700 (PDT),
> >> <dzogche...@[EMAIL PROTECTED]
> wrote in
> >>
<news:de9d8f03-80df-432e-9a5f-04eb2a979a24@[EMAIL PROTECTED]
>
> >> in alt.math.undergrad:
> >>> I have been swatting up using a book I purchased, which
> >>> has a question about area:
>
> I didn't notice this before, but it's the source of your
> trouble: this is *not* a problem about area. =A0See below.
>
> >>> How much will it cost to build a wall round a house that
> >>> is 25 metres long and 75 metres wide, if the cost of 50
> >>> cm is =A310? Your options are A) =A34,000, B) 40,000 or C)
> >>> =A3400. =A0The answers are meant to be estimations,
> >>> What is the answer? I have calculated the answer, but when I checked
> >>> it I found I was wrong, but I cannot get the supposed answer. =A0I
am
> >>> trying to just work out if the book is wrong or not.
> >> The wall is to be 25 + 75 + 25 + 75 =3D 200 metres long. =A0Each
> >> half-metre costs =A310, and the wall is 400 half-metres long,
> >> so ... .
> > OK, I didnt do that. =A0I took 25 * 75 which gives you 1875 m. =A0
>
> No, it gives an *area* of 1875 *square* metres within the
> fence/
>
> [...]
>
> > I thought this was an area question, hence 25 * 75....so I
> > need to think about what you did with just the additions,
>
> The fence has two short sides of 25 m. each and two long
> sides of 75 m. each; I just added up the lengths of these
> four sides.
>
> > I obviously dont understand the question!
>
> You need to keep your units straight. =A0The price is quoted
> in pounds per unit of length, not pounds per unit of area,
> so to get a total price, you clearly need to find a length
> -- the length of fencing required. =A0When you multiply two
> lengths in metres, however, you get an area.
>
> Brian
Drat! Of course...aarrgh....thanks for pointing my errors out, thats
very helpful. Will need to pay attention to what I read more!
Thanks agian,
D
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