On May 16, 9:39=A0pm, "michalc...@[EMAIL PROTECTED]
" <michalc...@[EMAIL PROTECTED]
> wrote:
> On May 16, 8:23=A0am, Dom <DR...@[EMAIL PROTECTED]
> wrote:
>
>
>
>
>
> > On Apr 25, 7:36=A0am, Pubkeybreaker <pubkeybrea...@[EMAIL PROTECTED]
> wrote:
>
> > > On Apr 25, 2:58=A0am, Beliavsky <beliav...@[EMAIL PROTECTED]
> wrote:
>
> > > >http://www.nytimes.com/2008/04/25/science/25math.html
> > > > Study Suggests Math Teachers Scrap Balls and Slices
> > > > By Kenneth Chang
> > > > New York Times, April 25, 2008
>
> > > > 'One train leaves Station A at 6 p.m. traveling at 40 miles per
hour=
> > > > toward Station B. A second train leaves Station B at 7 p.m.
travelin=
g
> > > > on parallel tracks at 50 m.p.h. toward Station A. The stations are
4=
00
> > > > miles apart. When do the trains pass each other?
>
> > > > Entranced, perhaps, by those infamous hypothetical trains, many
> > > > educators in recent years have incor****ated more and more examples
> > > > from the real world to teach abstract concepts. The idea is that
> > > > making math more relevant makes it easier to learn.
>
> > > > That idea may be wrong, if researchers at Ohio State University
are
> > > > correct. An experiment by the researchers suggests that it might
be
> > > > better to let the apples, oranges and locomotives stay in the real
> > > > world and, in the classroom, to focus on abstract equations, in
this=
> > > > case 40 (t + 1) =3D 400 - 50t, where t is the travel time in hours
o=
f
> > > > the second train. (The answer is below.)'
>
> > > This claim is ridiculous. =A0Learning how to translate a verbal
> > > statement of the problem into equations is far more im****tant
> > > than the mindless manipulations used to solve (in this case)
> > > linear equations. =A0The latter only involves application of an
algori=
thm.
>
> > The claim is indeed ridiculous! =A0The im****tance of translating word
> > problems--identifying unknowns, defining variables, deriving
> > equations--is demonstrated by the following true incident that was
> > published in the April 1994 issue of The Mathematics Teacher and was
> > reprinted in the February 1996 issue of The American Mathematical
> > Monthly (p. 146).
>
> > "[...] a very young bright CPA [partner] called me into his office and
> > asked how a person could possibly calculate a bonus if the company's
> > formula required that the bonus be 15 percent of the net profit after
> > the bonus has been deducted!
> > I showed him the linear equation B =3D 0.15P/1.15. =A0He was
> > flabbergasted."
> >
> you should have shown hin the derivation.
>
> 1B =3D .15 (P-B)
> 1B =3D .15P - .15 B
> 1.15B =3D .15P
> B=3D.15P/1.15
I quoted the item exactly as it appeared in the Monthly, and I did not
want to elaborate on it. One can also define the variables.
Let P =3D the net profit before the bonus.
Let B =3D the required amount of the bonus.
Then P - B is the net profit after the bonus has been deducted.
|
