GMAT Changed on April 16th - Read about the latest changes here

 It is currently 26 May 2018, 08:21

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Is 1/x greater than 1/y?

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 45438
Is 1/x greater than 1/y? [#permalink]

### Show Tags

05 Nov 2017, 02:12
1
KUDOS
Expert's post
00:00

Difficulty:

35% (medium)

Question Stats:

59% (00:42) correct 41% (00:25) wrong based on 74 sessions

### HideShow timer Statistics

Is 1/x greater than 1/y?

(1) x is greater than 1.
(2) x is less than y.

_________________
Manager
Joined: 06 Aug 2017
Posts: 81
GMAT 1: 570 Q50 V18
GMAT 2: 610 Q49 V24
Re: Is 1/x greater than 1/y? [#permalink]

### Show Tags

05 Nov 2017, 06:13
Bunuel wrote:
Is 1/x greater than 1/y?

(1) x is greater than 1.
(2) x is less than y.

The answer should be C as follows.

(1) x is greater than 1.
Since only value of x is give, y can be anything
INSUFFICIENT

(2) x is less than y
Here, there will be 3 cases

Case 1: When both x and y are positive
E.G. let x=2 and y=3
$$\frac{1}{x}=\frac{1}{2}=0.5$$
$$\frac{1}{y}=\frac{1}{3}=0.333$$
in this case $$\frac{1}{x}>\frac{1}{y}$$

Case 2: When x is negative and y is positive
E.G. x = -2 and y=3
$$\frac{1}{x}=\frac{1}{(-2)}= -0.5$$
$$\frac{1}{y}=\frac{1}{3}=0.333$$
in this case $$\frac{1}{x}<\frac{1}{y}$$

Case 2: When both x and y are negative
E.G. x = -2 and y=-1 (Since x<y)
$$\frac{1}{x}=\frac{1}{(-2)}= -0.5$$
$$\frac{1}{y}=\frac{1}{(-1)}= -1$$
in this case $$\frac{1}{x}<\frac{1}{y}$$

ICUFFICIENT

Note: Case 3 was really not required to be considered as case 1 and case 2 themselves produced the conflicting results.

Combining both, the condition will become, x<y and x is greater than 1. This will be an spacial scenario of case 1 of statement 2 in the question.
Since x>1, both x and y will be positive
E.G. x=2 and y=3
$$\frac{1}{x}=\frac{1}{2}=0.5$$
$$\frac{1}{y}=\frac{1}{3}=0.333$$
in this case $$\frac{1}{x}>\frac{1}{y}$$

SUFFICIENTS

_________________

-------------------------------------------------------------------------------
Kudos are the only way to tell whether my post is useful.

GMAT PREP 1: Q47 V36 - 680

Veritas Test 1: Q43 V34 - 630
Veritas Test 2: Q46 V30 - 620
Veritas Test 3: Q45 V29 - 610
Veritas Test 4: Q49 V30 - 650

GMAT PREP 2: Q50 V34 - 700

Intern
Joined: 05 Dec 2016
Posts: 6
Re: Is 1/x greater than 1/y? [#permalink]

### Show Tags

05 Nov 2017, 07:20
Please correct me if I am wrong.

What the question is asking is 1/x > 1/y

So can we not say -x>-y
and hence x<y I think this is what they are asking.

So only B statement proves it.

Manager
Joined: 06 Aug 2017
Posts: 81
GMAT 1: 570 Q50 V18
GMAT 2: 610 Q49 V24
Re: Is 1/x greater than 1/y? [#permalink]

### Show Tags

05 Nov 2017, 11:34
1
KUDOS
meetsampat wrote:
Please correct me if I am wrong.

What the question is asking is 1/x > 1/y

So can we not say -x>-y
and hence x<y I think this is what they are asking.

So only B statement proves it.

Hi meetsampat,

You cant cross multiply variable unless you consider signs of those variable.

Here you have to consider the following cases.

1. Both x and y are positive
2. Both x and y are negative
3. x is positive, y is negative
4. x is negative and y is positive

Based on the signs of the variable, the inequality sign will change while doing cross-multiplication.
_________________

-------------------------------------------------------------------------------
Kudos are the only way to tell whether my post is useful.

GMAT PREP 1: Q47 V36 - 680

Veritas Test 1: Q43 V34 - 630
Veritas Test 2: Q46 V30 - 620
Veritas Test 3: Q45 V29 - 610
Veritas Test 4: Q49 V30 - 650

GMAT PREP 2: Q50 V34 - 700

Intern
Joined: 05 Dec 2016
Posts: 6
Re: Is 1/x greater than 1/y? [#permalink]

### Show Tags

05 Nov 2017, 13:04
Jabjagotabhisavera wrote:
meetsampat wrote:
Please correct me if I am wrong.

What the question is asking is 1/x > 1/y

So can we not say -x>-y
and hence x<y I think this is what they are asking.

So only B statement proves it.

Hi meetsampat,

You cant cross multiply variable unless you consider signs of those variable.

Here you have to consider the following cases.

1. Both x and y are positive
2. Both x and y are negative
3. x is positive, y is negative
4. x is negative and y is positive

Based on the signs of the variable, the inequality sign will change while doing cross-multiplication.

Yes... I did not think on signs..Thanks !!
Manager
Joined: 10 Dec 2011
Posts: 102
Location: India
Concentration: Finance, Economics
GMAT Date: 09-28-2012
WE: Accounting (Manufacturing)
Re: Is 1/x greater than 1/y? [#permalink]

### Show Tags

11 Nov 2017, 07:45
C.
for 1/x > 1/y, X has to be less than Y. And B says exactly that. Wait, if X is negative, signs change. Therefore, X also has to be positive. And A states exactly that. Therefore C.
Further, just for info, none can be 0 otherwise division wont be possible. But both the choices are complete in themselves and take care of that.
Re: Is 1/x greater than 1/y?   [#permalink] 11 Nov 2017, 07:45
Display posts from previous: Sort by