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Explanation for DS

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Source: — Data Sufficiency |
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by Nermal » Thu Sep 10, 2009 4:12 am
IMO A

Statement 1:
I assume it's y^3:
take an integer: e.g. (2): 2*2*2=8
take a fraction: e.g. (1/2): 1/2*1/2*1/2=1/(2^3)=1/8

Only an integer y will yield an integer y^3.

SUFFICIENT.

Statement 2:
3*y:
take an integer: e.g. (3):3*3=9
take a fraction: e.g. (1/3): 3*(1/3)=1

Y could be an integer or a fraction for 3*y to become an integer.

INSUFFICIENT.
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by bharathh » Thu Sep 10, 2009 5:30 am
Nermal wrote:IMO A

Only an integer y will yield an integer y^3.
That is not true . cuberoot(2)(not an integer) will give you an integer when cubed.

Statement 1 is not sufficient.

IMO answer is C

If you know that the number is an integer when cubed and when multiplied by an integer, it has to be an integer.

I am struggling to to think of any number that does not follow the case.
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by Nermal » Fri Sep 11, 2009 7:08 am
OMG...didn't think of cuberoots!
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