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Math Expert
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Robin invested a total of $12,000 in two investments, X and Y, so that [#permalink] ### Show Tags 22 Jun 2018, 00:55 1 9 00:00 Difficulty: 25% (medium) Question Stats: 73% (01:16) correct 27% (01:17) wrong based on 436 sessions ### HideShow timer Statistics Robin invested a total of$12,000 in two investments, X and Y, so that the investments earned the same amount of simple annual interest. How many dollars did Robin invest in investment Y ?

(1) Investment X paid 3 percent simple annual interest, and investment Y paid 6 percent simple annual interest.
(2) Robin invested more than $1,000 in investment X. NEW question from GMAT® Official Guide 2019 (DS02441) _________________ Math Expert Joined: 02 Aug 2009 Posts: 7022 Re: Robin invested a total of$12,000 in two investments, X and Y, so that  [#permalink]

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22 Jun 2018, 02:25
2
1
Bunuel wrote:
Robin invested a total of $12,000 in two investments, X and Y, so that the investments earned the same amount of simple annual interest. How many dollars did Robin invest in investment Y ? (1) Investment X paid 3 percent simple annual interest, and investment Y paid 6 percent simple annual interest. (2) Robin invested more than$1,000 in investment X.

NEW question from GMAT® Official Guide 2019

(DS02441)

Simple interest = PRT/100, where P is principal, R rate of interest and T is time..
Here time is 1 year, as we are looking at simple annual interest..
SAI=PR/100..

1) statement I gives the two rate of interest as 3 and 6..
So z*3/100=(12000-z)*6/100..
It's a linear equation in z, you can find the value of z
Sufficient
2) statement II tells us that Robin invested $1000 more.. Nothing much Insufficient A _________________ 1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372 2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html 3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html GMAT online Tutor Manager Joined: 10 Jun 2018 Posts: 54 Location: Australia Concentration: Technology, General Management GPA: 2.88 WE: Science (Pharmaceuticals and Biotech) Re: Robin invested a total of$12,000 in two investments, X and Y, so that  [#permalink]

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22 Jun 2018, 02:27
Statement 1: If investment Y paid double the interest of investment X, then investment X must be double that of investment Y to get the same amount of interest earnt.

Therefore, the ratio of X:Y is 2:1, and so investment X is $8000, investment Y is$4000.

Statement 2 ain’t got enough info.

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Joined: 04 Jan 2015
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Re: Robin invested a total of $12,000 in two investments, X and Y, so that [#permalink] ### Show Tags 22 Jun 2018, 02:47 1 1 Solution Given: • Robin invested total$12000 in two investments, X and Y
• The investments earned same amount of simple annual interest

To find:
• The amount (dollars) Robin invested in Y

Analysing Statement 1
• As per the information given in statement 1, investment X paid 3% simple interest whereas investment Y paid 6% simple interest
• If we assume that investment in X is P, then investment in Y will be (12000 – P)
• As the simple annual interest earned is same, we can write:
o $$\frac{P * 3}{100} = \frac{(12000 – P) * 6}{100}$$
• We can get the value of P as well as (12000 – P)

Hence, statement 1 is sufficient to answer

Analysing Statement 2
• As per the information given in statement 2, Robin invested more than $1000 in investment X o From this, we cannot find out the exact investment in X and Y individually Hence, statement 2 is not sufficient to answer Hence, the correct answer is option A. Answer: A _________________ Register for free sessions Number Properties | Algebra |Quant Workshop Success Stories Guillermo's Success Story | Carrie's Success Story Ace GMAT quant Articles and Question to reach Q51 | Question of the week Must Read Articles Number Properties – Even Odd | LCM GCD | Statistics-1 | Statistics-2 Word Problems – Percentage 1 | Percentage 2 | Time and Work 1 | Time and Work 2 | Time, Speed and Distance 1 | Time, Speed and Distance 2 Advanced Topics- Permutation and Combination 1 | Permutation and Combination 2 | Permutation and Combination 3 | Probability Geometry- Triangles 1 | Triangles 2 | Triangles 3 | Common Mistakes in Geometry Algebra- Wavy line | Inequalities Practice Questions Number Properties 1 | Number Properties 2 | Algebra 1 | Geometry | Prime Numbers | Absolute value equations | Sets | '4 out of Top 5' Instructors on gmatclub | 70 point improvement guarantee | www.e-gmat.com CEO Joined: 11 Sep 2015 Posts: 3108 Location: Canada Re: Robin invested a total of$12,000 in two investments, X and Y, so that  [#permalink]

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23 Jun 2018, 06:35
1
Top Contributor
Bunuel wrote:
Robin invested a total of $12,000 in two investments, X and Y, so that the investments earned the same amount of simple annual interest. How many dollars did Robin invest in investment Y ? (1) Investment X paid 3 percent simple annual interest, and investment Y paid 6 percent simple annual interest. (2) Robin invested more than$1,000 in investment X.

Let X = The number of dollars invested in investment X
Let Y = The number of dollars invested in investment Y

Target question: What is the value of Y?

Given: Robin invested a total of $12,000 in two investments, X and Y, so that the investments earned the same amount of simple annual interest. If the total investment is$12,000, we can write: X + Y = 12,000

Statement 1: Investment X paid 3 percent simple annual interest, and investment Y paid 6 percent simple annual interest.
So, the annual interest paid by investment X = 0.03X and the interest paid by investment Y = 0.06Y
Since the annual interest on the two investments are EQUAL, we can write: 0.03X = 0.06Y
We now have the following system of linear equations:
X + Y = 12,000
0.03X = 0.06Y
Since we COULD solve this system for Y, we COULD answer the target question with certainty (but we would never waste valuable time actually solving the system!)
Since we could answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: Robin invested more than $1,000 in investment X. Since we don't know the exact value of the amount Robin invested in X, and since we don't know anything about the interest rates for the investments, we cannot answer the target question with certainty. So, statement 2 is NOT SUFFICIENT ASIDE: If you're not convinced that statement 2 is not sufficient, consider these two cases: Case a: X = 6,000, Y = 6,000, and the interest rate for each investment is 10%. Notice that the interest for each investment will be equal. Here, the answer to the target question is Y = 6,000 Case b: X = 2000, Y = 10,000, the interest rate for investment X is 50%, and the interest rate for investment Y is 10%. Notice that the interest for each investment will be equal. Here, the answer to the target question is Y = 10,000 Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT Answer: A Cheers, Brent _________________ Brent Hanneson – GMATPrepNow.com Intern Joined: 06 May 2015 Posts: 46 Location: India Schools: Darden '21 GPA: 4 Re: Robin invested a total of$12,000 in two investments, X and Y, so that  [#permalink]

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16 Sep 2018, 09:33
Bunuel wrote:
Robin invested a total of $12,000 in two investments, X and Y, so that the investments earned the same amount of simple annual interest. How many dollars did Robin invest in investment Y ? (1) Investment X paid 3 percent simple annual interest, and investment Y paid 6 percent simple annual interest. (2) Robin invested more than$1,000 in investment X.

NEW question from GMAT® Official Guide 2019

(DS02441)

(a)
X+Y = 12000
0.03X = 0.06Y
X = 2Y
Hence solvable, Suffficient

(b)
X>1000 -> Not sufficient