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Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
26 Oct 2012, 13:02

Expert's post

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Difficulty:

55% (hard)

Question Stats:

68% (03:30) correct
32% (02:34) wrong based on 103 sessions

Ms. Morris invested in Fund A and Fund B. The total amount she invested, in both funds combined, was $100,000. In one year, Fund A paid 23% and Fund B paid 17%. The interest earned in Fund B was exactly $200 greater than the interest earned in Fund A. How much did Ms. Morris invest in Fund A? (A) $32,000 (B) $36,000 (C) $40,000 (D) $42,000 (E) $45,000

For this question, one could do an algebraic solution, but would it be faster to backsolve from the answers? I would argue for the latter, though I imagine there will be a difference of opinions on this question.

Ms. Morris invested in Fund A and Fund B. The total amount she invested, in both funds combined, was $100,000. In one year, Fund A paid 23% and Fund B paid 17%. The interest earned in Fund B was exactly $200 greater than the interest earned in Fund A. How much did Ms. Morris invest in Fund A? (A) $32,000 (B) $36,000 (C) $40,000 (D) $44,000 (E) $45,000

For this question, one could do an algebraic solution, but would it be faster to backsolve from the answers? I would argue for the latter, though I imagine there will be a difference of opinions on this question.

Perhaps other experts would also like to chime in on the issue of when to solve algebraically vs. when to backsolve.

Mike

The correct answer should be 42,000, and it is not listed neither above, nor in the question you published on your blog. It just appears in the solution you posted. _________________

PhD in Applied Mathematics Love GMAT Quant questions and running.

Re: Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
02 Feb 2013, 15:35

1

This post received KUDOS

chibimoon wrote:

Could someone post the algebraic way please

A+B=100,000

0.17B=0.23A+200

You now have two equations, so you can either substitute or eliminate. In the explanation above, elimination is used, here I use substitution (elimination is easier in this case)

Take away decimals first: 17B=23A+20,000

Isolate first equation to solve for A (your goal): B=100,000-A

Plug in for B: 17(100,000-A)=23A+20,000 1,700,000-17A=23A+20,000 1,680,000=40A 1,680,000/40=A A=42,000=Answer Choice D _________________

"How far that little candle throws his beams. So shines a good deed in a weary world." - Shakespeare

The correct answer should be 42,000, and it is not listed neither above, nor in the question you published on your blog. It just appears in the solution you posted.

Yes, you're right --- a mistake on my part --- the OA is $42,000, and I just corrected the question above & the blog. Thank you very much.

Re: Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
02 May 2013, 10:29

Expert's post

Here's another problem from that same article, one that's even less amenable to algebraic treatment.

If the sequence a(n) is defined as a(n) = n^2 + n + \sqrt{n+3}, then which of the following values of n represents the first terms such that a(n) > 500? (A) 13 (B) 22 (C) 33 (D) 46 (E) 78