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Magoosh GMAT Instructor
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Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
 26 Oct 2012, 14:02
Question Stats:
66% (03:59) correct
33% (02:12) wrong based on 17 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) $45,000For 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. My argument, along with a discussion of backsolving in general and a complete solution to this problem, is here: http://magoosh.com/gmat/2012/gmat-plugg ... -choice-c/Perhaps other experts would also like to chime in on the issue of when to solve algebraically vs. when to backsolve. Mike 
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Mike McGarry
Magoosh Test Prep
Last edited by mikemcgarry on 26 Oct 2012, 16:28, edited 1 time in total.
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mikemcgarry wrote: 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) $45,000For 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. My argument, along with a discussion of backsolving in general and a complete solution to this problem, is here: http://magoosh.com/gmat/2012/gmat-plugg ... -choice-c/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.
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Magoosh GMAT Instructor
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EvaJager wrote: 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. Mike
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Mike McGarry
Magoosh Test Prep
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Re: Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
16 Nov 2012, 13:07
Could someone post the algebraic way please
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Re: Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
16 Nov 2012, 14:07
chibimoon wrote: Could someone post the algebraic way please A+B=100k 0.17B=0.23A+200=> -23A+17B=20000 from first equation 23A+23B=2300K add above and eq2 40B=2320K B=58K A=100k-58k=42k
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Re: Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
02 Feb 2013, 16:35
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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
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Magoosh GMAT Instructor
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Re: Ms. Morris invested in Fund A and Fund B. The total amount [#permalink]
02 May 2013, 11:29
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) 78A full solution is shown at that that article: http://magoosh.com/gmat/2012/gmat-plugg ... -choice-c/Mike
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Mike McGarry
Magoosh Test Prep
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Re: Ms. Morris invested in Fund A and Fund B. The total amount
[#permalink]
02 May 2013, 11:29
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