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# When x and y are integers, a3b4=c, a=?

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Math Revolution GMAT Instructor
Joined: 16 Aug 2015
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When x and y are integers, a3b4=c, a=?  [#permalink]

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05 Jun 2016, 19:32
1
00:00

Difficulty:

45% (medium)

Question Stats:

64% (01:31) correct 36% (01:17) wrong based on 51 sessions

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When x and y are integers, a^3*b^4=c, a=?
1) c=5,000
2) b=5

*An answer will be posted in 2 days.

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"Only $149 for 3 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Senior Manager Joined: 18 Jan 2010 Posts: 251 Re: When x and y are integers, a3b4=c, a=? [#permalink] ### Show Tags 05 Jun 2016, 22:03 MathRevolution wrote: When x and y are integers, a^3*b^4=c, a=? 1) c=5,000 2) b=5 *An answer will be posted in 2 days. I am assuming that all a, b and c are integers. (not x, y, as given) Then Statement 1 can be written as 5000 = 5 * $$10^3$$ = 5*$$2^3$$ * $$5^3$$ $$2^3$$ * $$5^4$$ If we take 1 as an integer, we wont get correct one to one correspondence. So a has to be 2. Sufficient. Statement 2 is clearly insufficient. A is the answer. Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 7226 GMAT 1: 760 Q51 V42 GPA: 3.82 When x and y are integers, a3b4=c, a=? [#permalink] ### Show Tags 07 Jun 2016, 18:47 There are three (a,b,c) variables and one equation (a^3b^4=c) in the original condition. In order to match the number of variables and the number of equations, we need 2 equations. There is, thus, high chance that C is the correct answer. Using the condition 1) and the condition 2), we get a=2. The answer is unique and the condition is sufficient. However, since this is one of key questions, integer question, we have to apply the common mistake type 4(A). From the condition 1), we get a^3b^4=5,000=2^35^4. The answer is a=2. The answer is unique and the condition is sufficient. Hence, the correct answer is A. - Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution. _________________ MathRevolution: Finish GMAT Quant Section with 10 minutes to spare The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. "Only$149 for 3 month Online Course"
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Re: When x and y are integers, a3b4=c, a=?  [#permalink]

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19 Jul 2017, 10:16
Ans is A....

Kindly correct the question When x and y are integers should be When a and b are integers
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Re: When x and y are integers, a3b4=c, a=?   [#permalink] 19 Jul 2017, 10:16
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