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If money is invested at r percent interest, compounded annua [#permalink]
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17 Dec 2012, 06:46
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If money is invested at r percent interest, compounded annually, the amount of the investment will double in approximately 70/r years. If Pat's parents invested $5,000 in a longterm bond that pays 8 percent interest, compounded annually, what will be the approximate total amount of the investment 18 years later, when Pat is ready for college? (A) $20000 (B) $15000 (C) $12000 (D) $10000 (E) $9000
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Re: If money is invested at r percent interest, compounded annua [#permalink]
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17 Dec 2012, 06:48
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Walkabout wrote: If money is invested at r percent interest, compounded annually, the amount of the investment will double in approximately 70/r years. If Pat's parents invested $5,000 in a longterm bond that pays 8 percent interest, compounded annually, what will be the approximate total amount of the investment 18 years later, when Pat is ready for college?
(A) $20000 (B) $15000 (C) $12000 (D) $10000 (E) $9000 Since investment doubles in 70/r years, then for r=8 it'll double in 70/8=~9 years (we are not asked about the exact amount so such an approximation will do). Thus in 18 years investment will double twice and become ($5,000*2)*2=$20,000 (after 9 years investment will become $5,000*2=$10,000 and in another 9 years it'll become $10,000*2=$20,000). Answer: A.
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Re: If money is invested at r percent interest, compounded annua [#permalink]
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25 Jun 2014, 12:12
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Re: If money is invested at r percent interest, compounded annua [#permalink]
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25 Jun 2014, 23:37
It's very important to pay attention to the wordings as first I thought that the compound interest formula needs to be applied. Though I read the question again and got it correct Posted from my mobile device



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Re: If money is invested at r percent interest, compounded annua [#permalink]
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24 Aug 2014, 15:25
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I think without the 1st sentence, we still can guess the answer easily.
$5,000 at 8%/year = $400/year > 10years interest will be $4,000, 20 years will be $8,000 Since the interest compounded annually in 18 years (very long period), the total value would be >$18,000 > eliminate B,C,D,E



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Re: If money is invested at r percent interest, compounded annua [#permalink]
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10 Oct 2014, 20:42
should be so easy for business students...especially finance



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Re: If money is invested at r percent interest, compounded annua [#permalink]
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22 Oct 2014, 00:35
5000 will multiply approx. 4 times = 5000 * 4 = 20000 Answer = A
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Re: If money is invested at r percent interest, compounded annua [#permalink]
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22 Dec 2015, 11:12
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Re: If money is invested at r percent interest, compounded annua [#permalink]
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25 Dec 2015, 12:07
Hi All, This question has some similarities to "symbolism" questions (in which the prompt shows you a "made up" symbol, tells you what it means and asks you to do a simple calculation with it). The easiest way to tackle the question is to simply follow the instructions. We're told that r = percent interest. We're also told that an investment with DOUBLE in approximately 70/r years. We're told to invest $5,000 at 8 percent for 18 years. Plug in r = 8 70/8 is about 9 years, meaning our investment will DOUBLE in 9 years. In the first 9 years, $5,000 doubles to $10,0000 In the next 9 years, $10,000 doubles to $20,000 Final Answer: GMAT assassins aren't born, they're made, Rich
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Re: If money is invested at r percent interest, compounded annua [#permalink]
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16 Jun 2016, 06:11
Walkabout wrote: If money is invested at r percent interest, compounded annually, the amount of the investment will double in approximately 70/r years. If Pat's parents invested $5,000 in a longterm bond that pays 8 percent interest, compounded annually, what will be the approximate total amount of the investment 18 years later, when Pat is ready for college?
(A) $20000 (B) $15000 (C) $12000 (D) $10000 (E) $9000 Although this question appears as if we may have to do a lot of calculating, we actually do not. Focus on the first sentence of the question stem. We are given that if money is invested at r percent interest, compounded annually, the amount of investment will double in approximately 70/r years. We are then given that Pat’s parents invest $5,000 at 8 percent interest. It follows that the investment will double after 70/8 years, which is roughly 9 years. With an initial investment of $5,000, the investment will double to $10,000 in about 9 years. In another 9 years (a total of 18 years) the investment will double again to about $20,000. Answer A
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