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Re: [Phys-L] just for fun

On 12/19/2013 08:27 AM, Ken Caviness wrote:
That's effectively the way I automatically saw the problem, too:

25/28 <=?=> 15/17 [1]

1 - 2/28 <=?=> 1 - 2/17 [2]

Yeah, but the devil is in the details. Equation [2[ does not
follow from [1]. It should involve 3/28 (not 2/28 ... and
not 3/18). Typos will bite you every time. The correct
comparison is

3/28 versus 2/17 [3]

which are numerically rather close, so it pays to be careful.
They were intentionally /constructed/ to be rather close.

On 12/19/2013 08:35 AM, Anthony Lapinski wrote:

This is all very nice and interesting, but kids don't think like this.
They're not taught
to deal with fractions like this

Agreed. This was explicitly billed as *not* suitable as a placement
test question.

OTOH the skills we are talking about can be learned, and can be taught.