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# Is x < y?

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Intern
Joined: 03 Mar 2018
Posts: 36
Is x < y? [#permalink]

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05 Mar 2018, 07:22
3
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Difficulty:

55% (hard)

Question Stats:

61% (02:04) correct 39% (01:06) wrong based on 33 sessions

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Is x < y?

(1) $$\frac{1}{x}$$ < $$\frac{1}{y}$$

(2) x + y = 10
[Reveal] Spoiler: OA
Math Expert
Joined: 02 Aug 2009
Posts: 5713
Is x < y? [#permalink]

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05 Mar 2018, 07:38
Expert's post
1
This post was
BOOKMARKED
itisSheldon wrote:
Is x < y?

(1) $$\frac{1}{x}$$ < $$\frac{1}{y}$$

(2) x + y = 10

(1) $$\frac{1}{x}$$ < $$\frac{1}{y}$$....
a) if both x and y are POSITIVE $$\frac{1}{x}$$ < $$\frac{1}{y}.....y<x$$....
b) if x is NEGATIVE and y is POSITIVE $$\frac{1}{x}$$ < $$\frac{1}{y}.....y>x$$....
so insuff

(2) x + y = 10
nothing at all..
insuff

combined
both positive..
x = 6 and y = 4.. x>y possible

both negative .. Not possible
x negative and y positive..
x=-2 and y=12... x<y

insuff

E
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

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Math Expert
Joined: 02 Sep 2009
Posts: 44290
Is x < y? [#permalink]

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05 Mar 2018, 08:02
Expert's post
1
This post was
BOOKMARKED
chetan2u wrote:
itisSheldon wrote:
Is x < y?

(1) $$\frac{1}{x}$$ < $$\frac{1}{y}$$

(2) x + y = 10

(1) $$\frac{1}{x}$$ < $$\frac{1}{y}$$....
a) if both x and y are POSITIVE$$\frac{1}{x}$$ < $$\frac{1}{y}.....y<x$$....
b) if both x and y are NEGATIVE$$\frac{1}{x}$$ < $$\frac{1}{y}.....y>x$$....
so insuff

(2) x + y = 10
nothing at all..
insuff

combined
both positive..
x = 6 and y = 4.. x>y possible

both negative .. Not possible
x negative and y positive..
x=-2 and y=12.. x<y

insuff

E

The red part is not correct.

Is x < y?

(1) $$\frac{1}{x} < \frac{1}{y}$$.

If x and y have the same sign, then y < x.
If x and y have the opposite signs (so when x is negative and y is positive, because the reverse is not possible), then y > x.

Not sufficient.

(2) x + y = 10. Clearly not sufficient.

(1)+(2) x and y could still have the same sign, for example, consider x = 6 and y = 4 (in this case y < x) as well as they could have the opposite signs, for example, x = -1 and y = 11 (in this case y > x). Not sufficient.

_________________
Math Expert
Joined: 02 Aug 2009
Posts: 5713
Re: Is x < y? [#permalink]

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05 Mar 2018, 08:09
1
KUDOS
Expert's post
Bunuel wrote:
chetan2u wrote:
itisSheldon wrote:
Is x < y?

(1) $$\frac{1}{x}$$ < $$\frac{1}{y}$$

(2) x + y = 10

(1) $$\frac{1}{x}$$ < $$\frac{1}{y}$$....
a) if both x and y are POSITIVE$$\frac{1}{x}$$ < $$\frac{1}{y}.....y<x$$....
b) if both x and y are NEGATIVE$$\frac{1}{x}$$ < $$\frac{1}{y}.....y>x$$....
so insuff

(2) x + y = 10
nothing at all..
insuff

combined
both positive..
x = 6 and y = 4.. x>y possible

both negative .. Not possible
x negative and y positive..
x=-2 and y=12.. x<y

insuff

E

The red part is not correct.

Is x < y?

(1) $$\frac{1}{x} < \frac{1}{y}$$.

If x and y have the same sign, then y < x.
If x and y have the opposite signs (so when x is negative and y is positive, because the reverse is not possible), then y > x.

Not sufficient.

(2) x + y = 10. Clearly not sufficient.

(1)+(2) x and y could still have the same sign, for example, consider x = 6 and y = 4 (in this case y < x) as well as they could have the opposite signs, for example, x = -1 and y = 11 (in this case y > x). Not sufficient.

Thanks Bunuel...
it was typo because of copy and paste of previous statement..
it meant x negative and y positive as also given in the Combined portion..
_________________

Absolute modulus :http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html

GMAT online Tutor

Re: Is x < y?   [#permalink] 05 Mar 2018, 08:09
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# Is x < y?

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