GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 10 Dec 2018, 12:24

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
  • Free lesson on number properties

     December 10, 2018

     December 10, 2018

     10:00 PM PST

     11:00 PM PST

    Practice the one most important Quant section - Integer properties, and rapidly improve your skills.
  • Free GMAT Prep Hour

     December 11, 2018

     December 11, 2018

     09:00 PM EST

     10:00 PM EST

    Strategies and techniques for approaching featured GMAT topics. December 11 at 9 PM EST.

Is 1/x greater than 1/y?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 51072
Is 1/x greater than 1/y?  [#permalink]

Show Tags

New post 05 Nov 2017, 01:12
1
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

67% (01:01) correct 33% (00:46) wrong based on 78 sessions

HideShow timer Statistics

Manager
Manager
avatar
B
Joined: 06 Aug 2017
Posts: 86
GMAT 1: 570 Q50 V18
GMAT 2: 610 Q49 V24
GMAT 3: 640 Q48 V29
Re: Is 1/x greater than 1/y?  [#permalink]

Show Tags

New post 05 Nov 2017, 05:13
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

Hence, answer is C
_________________

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

GMAT PREP 1: Q50 V34 - 700

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

Veritas Test 5: Q47 V33 - 650
Veritas Test 5: Q46 V33 - 650

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

Show Tags

New post 05 Nov 2017, 06:20
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.

Please advise. Thanks
Manager
Manager
avatar
B
Joined: 06 Aug 2017
Posts: 86
GMAT 1: 570 Q50 V18
GMAT 2: 610 Q49 V24
GMAT 3: 640 Q48 V29
Re: Is 1/x greater than 1/y?  [#permalink]

Show Tags

New post 05 Nov 2017, 10:34
1
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.

Please advise. Thanks


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: Q50 V34 - 700

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

Veritas Test 5: Q47 V33 - 650
Veritas Test 5: Q46 V33 - 650

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

Show Tags

New post 05 Nov 2017, 12:04
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.

Please advise. Thanks


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
Manager
avatar
S
Joined: 10 Dec 2011
Posts: 89
Location: India
Concentration: Finance, Economics
GMAT Date: 09-28-2012
WE: Accounting (Manufacturing)
Re: Is 1/x greater than 1/y?  [#permalink]

Show Tags

New post 11 Nov 2017, 06:45
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.
GMAT Club Bot
Re: Is 1/x greater than 1/y? &nbs [#permalink] 11 Nov 2017, 06:45
Display posts from previous: Sort by

Is 1/x greater than 1/y?

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.