GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 04 Aug 2020, 04:11

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

Is x = 1/y?

Author Message
TAGS:

Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 65785

Show Tags

21 Oct 2015, 20:33
5
3
00:00

Difficulty:

5% (low)

Question Stats:

93% (00:33) correct 7% (00:46) wrong based on 1543 sessions

HideShow timer Statistics

Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

_________________
Marshall & McDonough Moderator
Joined: 13 Apr 2015
Posts: 1664
Location: India
Re: Is x = 1/y?  [#permalink]

Show Tags

21 Oct 2015, 22:12
1
Is x = 1/y ? --> Is x - (1/y) = 0 --> Is xy = 1 ?

St1: Sufficient
St2: (1/xy) - 1 = 0 --> 1 - xy = 0 --> xy = 1... Sufficient

Retired Moderator
Joined: 29 Apr 2015
Posts: 748
Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE: Asset Management (Investment Banking)
Re: Is x = 1/y?  [#permalink]

Show Tags

23 Oct 2015, 00:15
2
Bunuel wrote:
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

1) Rewrite to get x = 1/y --> sufficient
2) Multiply by x to get x = 1/y --> sufficient

Manager
Joined: 13 Mar 2013
Posts: 153
Location: United States
GPA: 3.5
WE: Engineering (Telecommunications)
Re: Is x = 1/y?  [#permalink]

Show Tags

23 Oct 2015, 19:41
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

From st 1
(1) xy = 1
there fore
x = 1/y

sufficient

From st 2
(2) 1/(xy) = 1

1/y = x ( simply rearranging the statement )

sufficient
hence D ans
_________________
Regards ,
Intern
Status: Don't watch the clock,Do what it does, Keep Going.
Joined: 10 Jan 2017
Posts: 37
Re: Is x = 1/y?  [#permalink]

Show Tags

18 Sep 2017, 01:26
1 rewrite to get x=1/y sufficient
2 rewrite or multiply by x on both the sides you get x=1/y sufficient
D
GMAT Club Legend
Joined: 11 Sep 2015
Posts: 4987
GMAT 1: 770 Q49 V46
Re: Is x = 1/y?  [#permalink]

Show Tags

10 Oct 2017, 07:54
Top Contributor
1
Bunuel wrote:
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

Target question: Is x = 1/y?

Statement 1: xy = 1
This tells us that y does NOT equal 0 (and x does NOT equal 0 too)
So, if we take xy = 1 and divide both sides by y, we get x = 1/y
PERFECT, this is exactly what we are looking for.
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: 1/(xy) = 1
This tells us that x and y do NOT equal 0
So, we can take 1/(xy) and multiply both sides by x to get 1/y = x
Also PERFECT!
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Cheers,
Brent
_________________
If you enjoy my solutions, you'll love my GMAT prep course.

Intern
Joined: 27 Dec 2018
Posts: 41
Location: India
GPA: 3.48
WE: General Management (Manufacturing)
Re: Is x = 1/y?  [#permalink]

Show Tags

11 Jan 2019, 02:05
Cross multiply the question and it becomes xy = 1
Now check the options
So both separately prove xy=1
Hence D

Intern
Joined: 17 Jan 2017
Posts: 19
GMAT 1: 540 Q42 V23
GPA: 3.85

Show Tags

31 May 2019, 04:07
Is there any problem for multiplying or dividing any variables without knowing the sign?? I found it in the inequality problem and now get confused. Please suggest me when to consider this principle?
CEO
Joined: 03 Jun 2019
Posts: 3339
Location: India
GMAT 1: 690 Q50 V34
WE: Engineering (Transportation)
Re: Is x = 1/y?  [#permalink]

Show Tags

16 Sep 2019, 02:19
Bunuel wrote:
Is x = 1/y?

(1) xy = 1
(2) 1/(xy) = 1

Kudos for a correct solution.

Is x = 1/y?

(1) xy = 1
x = 1/y
SUFFICIENT

(2) 1/(xy) = 1
x = 1/y
SUFFICIENT

IMO D
_________________
Kinshook Chaturvedi
Email: kinshook.chaturvedi@gmail.com
examPAL Representative
Joined: 07 Dec 2017
Posts: 1151
Re: Is x = 1/y?  [#permalink]

Show Tags

16 Sep 2019, 03:43
sajon wrote:
Is there any problem for multiplying or dividing any variables without knowing the sign?? I found it in the inequality problem and now get confused. Please suggest me when to consider this principle?

no - you just have to make sure you multiply both sides by the same thing.
There is a problem in inequalities - not in equations.
_________________
Re: Is x = 1/y?   [#permalink] 16 Sep 2019, 03:43