Inequality-MGMAT

[selango]

Is x > y?

(1) sqrt(x)> y

(2) x^3 > y

OA C

[kvcpk]

Is x > y?

(1) sqrt(x)> y

(2) x^3 > y

OA C

sqrt(x)> y
let x=16, y =3
4>3

16>3....YES

Let x=0.25, y=0.4
0.5>0.4

0.25<0.4...NO

INSUFF

x^3 > y

let x=2, y=1
8>1

2>1....YES

let x=-1/2,y=-1/4
-1/8>-1/4

-1/2<-1/4...NO

INSUFF

combining:
X can be positive or negative or fraction or 0
X cannot be negative because sqrt(x) will not hold.
If x is 0, then y has to be negative to satisfy both the eqtns. hence X>Y

Now, If X is fraction, then stmt1 will fail. So, we cant input fractions.

Now, we are only left with positives. For positives, answer in oth the statements is YES.

Hence pick C.

[gmatmachoman]

Is x > y?

(1) sqrt(x)> y

(2) x^3 > y

OA C

sqrt(x)> y
let x=16, y =3
4>3

16>3....YES

Let x=0.25, y=0.4
0.5>0.4

0.25<0.4...NO

INSUFF

x^3 > y

let x=2, y=1
8>1

2>1....YES

let x=-1/2,y=-1/4
-1/8>-1/4

-1/2<-1/4...NO

INSUFF

combining:
X can be positive or negative or fraction or 0
X cannot be negative because sqrt(x) will not hold.
If x is 0, then y has to be negative to satisfy both the eqtns. hence X>Y

Now, If X is fraction, then stmt1 will fail. So, we cant input fractions.

Now, we are only left with positives. For positives, answer in oth the statements is YES.

Hence pick C.

pravven, plz tell how much time u took for this prblm??

I suppose not less than 3 mins!!

[kvcpk]

pravven, plz tell how much time u took for this prblm??

I suppose not less than 3 mins!!

Yeah.. I took 3-4 minutes. I believe its one of those tougher problems.
Sorting out cases for A and B took nearly 2 mins.

But the combining part kept me puzzled. Using Algebra I think it is bit more difficult to prove.
I tried the algebraic way for a minute. I was not arriving anywhere close. So went back to logic.