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Magoosh GMAT Instructor
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Ms. Morris invested in Fund A and Fund B. The total amount
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Updated on: 26 Oct 2012, 15:28
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73% (02:36) correct 27% (02:43) wrong based on 269 sessions
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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/gmatplugg ... choicec/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
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Originally posted by mikemcgarry on 26 Oct 2012, 13:02.
Last edited by mikemcgarry on 26 Oct 2012, 15:28, edited 1 time in total.



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Re: backsolving
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26 Oct 2012, 14:42
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/gmatplugg ... choicec/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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Re: backsolving
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26 Oct 2012, 15:30
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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Education is not the filling of a pail, but the lighting of a fire. — William Butler Yeats (1865 – 1939)



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Re: Ms. Morris invested in Fund A and Fund B. The total amount
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16 Nov 2012, 12:07
Could someone post the algebraic way please



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Re: Ms. Morris invested in Fund A and Fund B. The total amount
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16 Nov 2012, 13:07
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=100k58k=42k



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Re: Ms. Morris invested in Fund A and Fund B. The total amount
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02 Feb 2013, 15:35
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=100,000A Plug in for B: 17(100,000A)=23A+20,000 1,700,00017A=23A+20,000 1,680,000=40A 1,680,000/40=A A=42,000=Answer Choice D
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Re: Ms. Morris invested in Fund A and Fund B. The total amount
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02 May 2013, 10:29
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/gmatplugg ... choicec/Mike
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Re: Ms. Morris invested in Fund A and Fund B. The total amount
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10 Sep 2016, 12:12
took some time as the numbers were high... 0.17B0.23A = 200  * 100 17B23A=20,000 A+B=100,000 B=100,000  A
17(100,000  A)  23A = 20,000 1,700,000  17A  23A = 20,000 1,680,000 = 40A divide by 40 first two digits: 42...so answer is D.



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Re: Ms. Morris invested in Fund A and Fund B. The total amount
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26 Sep 2016, 03:06
\(A + B = 100,000\)\(0.17B = 0.23A + 200 ==> 23A + 17B = 20,000\)For making our calculation easy, we can divide constant by factor of 1000 and get the result. \(A + B = 100\)==> \(17A + 17B = 1700\) {i) ==> \(23A + 17B = 20\) (ii) Subtract (ii) from (i) 17A  (23A) = 170020 40A = 1680 A =\(\frac{168}{4}\)= 42.A = 42,000
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Re: Ms. Morris invested in Fund A and Fund B. The total amount
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