If x and y are positive, is x^3 > y?
(1) sqrt x > y
(2) x > y
Are you sure this is posted correctly and/or the OA is correct?
Individually, both are insuff b/c there are some scenarios where x<1 where X or sqrtx can be greater than y but x^3 can be less than y. (try Y=.5 and then use X=.7 and X=100 to see what I mean)
In evaluting C, lets use X=.5 and Y=.3
sqrt x= ~.7 so it satisfies 1 and 2 b/c .7 and .5 are greater than .3 However, if we take x^3, we get .5x.5x.5 = .125<Y. If we plug in X=100, X^3 is clearly greater than Y. So E, insuff.
Would love to know if anyone disagrees/if I'm misreading...thanks
power and inequality
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Source: Beat The GMAT — Data Sufficiency |
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sudhir3127
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even i think its E. can u please share the source of the question!!ska7945 wrote:If x and y are positive, is x^3 > y?
(1) sqrt x > y
(2) x > y
oa C
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parallel_chase
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Statement I
sqrtx = 1/2
y=1/4
sqrt x > y
x^3=1/8
x^3<y
No.
sqrtx = 2
x=4
y=5
x^3=64
y=5
x^3>y
Yes.
Insufficient.
Statment II
x>y
x=4
y=3
x^3=64
x^3>y
Yes.
x=1/2
y=1/4
x^3=1/8
x^3<y
No.
Insufficient.
Combining I & II
sqrt x > y
x > y
x=4
y=1
sqrtx =2
x^3>y
Yes.
x=1/4
sqrtx=1/2
y=1/8
1/4>1/8
1/2>1/8
1/8=1/8
x^3=y
No.
Insufficient.
Hence E.
The OA is wrong unless the question is posted incorrectly.
Whats the source.
sqrtx = 1/2
y=1/4
sqrt x > y
x^3=1/8
x^3<y
No.
sqrtx = 2
x=4
y=5
x^3=64
y=5
x^3>y
Yes.
Insufficient.
Statment II
x>y
x=4
y=3
x^3=64
x^3>y
Yes.
x=1/2
y=1/4
x^3=1/8
x^3<y
No.
Insufficient.
Combining I & II
sqrt x > y
x > y
x=4
y=1
sqrtx =2
x^3>y
Yes.
x=1/4
sqrtx=1/2
y=1/8
1/4>1/8
1/2>1/8
1/8=1/8
x^3=y
No.
Insufficient.
Hence E.
The OA is wrong unless the question is posted incorrectly.
Whats the source.
