please help me with these tricky DS

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by Ian Stewart » Tue Aug 26, 2008 2:17 am
jeffxujian wrote:
Ian Stewart wrote:I'm pretty sure Q3 is supposed to read:

Q3. Is x>k?
1. (2^x)(2^k)=4
2. (9^x)(3^k)=81.

Then the statements are not contradictory.
Ian:

Is the correct answer of the above question C?

1. x+k=4 insufficient, because x, k can be any numbers
2.2x+k=4 insufficient, same drill as above

combine 1 with 2, x=0 and K=4, thus the result is sufficient to answer question whether x is greater than k.

Please correct me if i made any mistakes. Thank!
Yes, it is C, though your first equation should read x+k = 2. If you solve, you should find x=2 and k=0.

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by jeffxujian » Tue Aug 26, 2008 3:29 am
Hi, Ian

Thanks for the correction. I believe that is also something for which i should watch out on the GMAT.

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Re: please help me with these tricky DS

by gmattester » Tue Aug 26, 2008 6:50 am
saeed wrote: Q3. Is x>k?
1. (2x)(2k)=4
2. (9x)(3k)=81.

Please help me with most efficient approach.
Thanks in advance.
Can somone verify answer to Q3. Is it C or E

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how is it that you arrived at the x+k=4 and 2x+k=4?
Ian Stewart wrote:
jeffxujian wrote:
Ian Stewart wrote:I'm pretty sure Q3 is supposed to read:

Q3. Is x>k?
1. (2^x)(2^k)=4
2. (9^x)(3^k)=81.

Then the statements are not contradictory.
Ian:

Is the correct answer of the above question C?

1. x+k=4 insufficient, because x, k can be any numbers
2.2x+k=4 insufficient, same drill as above

combine 1 with 2, x=0 and K=4, thus the result is sufficient to answer question whether x is greater than k.

Please correct me if i made any mistakes. Thank!
Yes, it is C, though your first equation should read x+k = 2. If you solve, you should find x=2 and k=0.