Puzzle on ratios

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burgess: Newbie | Next Rank: 10 Posts; Posts: 5; Joined: Sun Jun 22, 2014 11:48 pm

Puzzle on ratios

by burgess » Sun Jun 29, 2014 11:07 pm

Help me to solve my math problem

What least number must be subtracted from each of the numbers 14, 17 , 34 and 42, so that the remainders may be proportional?

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Source: Beat The GMAT — Problem Solving | Sun Jun 29, 2014 11:07 pm

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by [email protected] » Sun Jun 29, 2014 11:26 pm

Hi burgess,

There are a couple of problems with this question. First, it's NOT a GMAT question. Second, this question seems incomplete. To calculate a remainder, we need to have some idea of what we're "dividing by."

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Rich

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GMATinsight: Legendary Member; Posts: 1100; Joined: Sat May 10, 2014 11:34 pm; Location: New Delhi, India; Thanked: 205 times; Followed by:24 members

by GMATinsight » Sun Jun 29, 2014 11:56 pm

Let the required number be x.

Then, (14 - x) : (17 - x) : : (34 - x) : (42 - x).

(14 - x) * (42 - x) = (17 - x) * (34 - x)

=> x^2 - 56x + 588 = x^2 - 51x + 578

5x = 10

x = 2

Required number = 2.

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GMATinsight: Legendary Member; Posts: 1100; Joined: Sat May 10, 2014 11:34 pm; Location: New Delhi, India; Thanked: 205 times; Followed by:24 members

by GMATinsight » Sun Jun 29, 2014 11:59 pm

But "TRUE", This is not a GMAT like question.

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by Brent@GMATPrepNow » Mon Jun 30, 2014 6:20 am

Hi Bhoopendra,

I'm not sure that we can assume that "proportional remainders" necessarily means comparing the 2 ratios that you compared in your solution.
Also, we typically don't use the word "remainder" to denote the difference between two values.

On a different note (to burgess), if this were a (better written) GMAT question, there would be 5 answer choices, so it would be easy to simply test the options. I'm assuming that you aren't actually preparing for the GMAT. Is that correct?

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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GMATinsight: Legendary Member; Posts: 1100; Joined: Sat May 10, 2014 11:34 pm; Location: New Delhi, India; Thanked: 205 times; Followed by:24 members

by GMATinsight » Mon Jun 30, 2014 7:00 am

Hi Brent,

Yes you are right... This is not the term used by GMAT.

In indian tests sometimes we use this word remainder for (A-B) if we have to refer to the result after B is subtracted from A. (Which linguistically correct however not used by GMAT in that scenario)

Therefore I mentioned it already that this question doesn't represent a questions of GMAT.