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DS (Number System)

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DS (Number System)

by rintoo22 » Sat Mar 23, 2013 7:40 am
If x and y are positive, is x^3 > y?
(1) x^1/2 > y
(2) x > y

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.

The correct answer is E. Are considering the value of x and y between 0<x<1 and 0<y<1 ?
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by Anju@Gurome » Sat Mar 23, 2013 7:45 am
rintoo22 wrote:If x and y are positive, is x^3 > y?
(1) x^1/2 > y
(2) x > y
Whenever comparison of powers are involved, always consider numbers greater than 1 as well as numbers less than 1.

Consider the following two cases,
  • x = 4 and y = 1 ---> x³ > y
    x = 1/4 and y = 1/8 ---> x³ < y
Both of the above examples satisfy both the statements.

The correct answer is E.
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by GMATGuruNY » Sun Mar 24, 2013 11:18 am
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