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

It is currently 14 Dec 2018, 07:50

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

Is n an integer?

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

Hide Tags

Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6639
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Is n an integer?  [#permalink]

Show Tags

New post 17 Aug 2018, 01:28
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

56% (01:06) correct 44% (00:46) wrong based on 54 sessions

HideShow timer Statistics

[Math Revolution GMAT math practice question]

Is \(n\) an integer?

1) \(3n\) is an integer
2) \(4n\) is an integer

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7106
Re: Is n an integer?  [#permalink]

Show Tags

New post 17 Aug 2018, 01:37
1
[quote="MathRevolution"][Math Revolution GMAT math practice question]

Is \(n\) an integer?

1) \(3n\) is an integer
It is possible if
# n is an integer
# n is a fraction with just 3 in DENOMINATOR, for example 1/3,2/3 etc
Insufficient

2) \(4n\) is an integer
It is possible if
# n is an integer
# n is a fraction with just 2 or 4 in DENOMINATOR, for example 1/2, 3/4 9/4 etc
Insufficient

Combined..
Only case left
n is an integer
Sufficient

C
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Senior Manager
Senior Manager
User avatar
P
Joined: 18 Jul 2018
Posts: 498
Location: India
Concentration: Finance, Marketing
WE: Engineering (Energy and Utilities)
Premium Member Reviews Badge CAT Tests
Re: Is n an integer?  [#permalink]

Show Tags

New post 17 Aug 2018, 05:22
chetan2u wrote:
MathRevolution wrote:
[Math Revolution GMAT math practice question]

Is \(n\) an integer?

1) \(3n\) is an integer
It is possible if
# n is an integer
# n is a fraction with just 3 in DENOMINATOR, for example 1/3,2/3 etc
Insufficient

2) \(4n\) is an integer
It is possible if
# n is an integer
# n is a fraction with just 2 or 4 in DENOMINATOR, for example 1/2, 3/4 9/4 etc
Insufficient

Combined..
Only case left
n is an integer
Sufficient


C


Hi sir,
Correct me if I'm wrong. On combining shouldn't we take the LCM of 3n and 4n which is 12n and n can be 1/12 or 1. Both yes or no is possible. Hence E is the answer?
_________________

When you want something, the whole universe conspires in helping you achieve it.

Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7106
Is n an integer?  [#permalink]

Show Tags

New post 17 Aug 2018, 05:37
Afc0892 wrote:
chetan2u wrote:
MathRevolution wrote:
[Math Revolution GMAT math practice question]

Is \(n\) an integer?

1) \(3n\) is an integer
It is possible if
# n is an integer
# n is a fraction with just 3 in DENOMINATOR, for example 1/3,2/3 etc
Insufficient

2) \(4n\) is an integer
It is possible if
# n is an integer
# n is a fraction with just 2 or 4 in DENOMINATOR, for example 1/2, 3/4 9/4 etc
Insufficient

Combined..
Only case left
n is an integer
Sufficient


C


Hi sir,
Correct me if I'm wrong. On combining shouldn't we take the LCM of 3n and 4n which is 12n and n can be 1/12 or 1. Both yes or no is possible. Hence E is the answer?



No you will take them separately..
if n=1/12, 3n=3*1/12=1/4 which is NOT an integer but 3n is an integer
So take 3n and 4n separately
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6639
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: Is n an integer?  [#permalink]

Show Tags

New post 19 Aug 2018, 17:43
=>

Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.

Condition 1)
If \(n = 1\), the answer is ‘yes’.
If \(n = \frac{1}{3}\), the answer is ‘no’.
Since we don’t have a unique solution, condition 1) is not sufficient.

Condition 2)
If \(n = 1\), the answer is ‘yes’.
If \(n = \frac{1}{4}\), the answer is ‘no’.
Since we don’t have a unique solution, condition 2) is not sufficient.

Conditions 1) & 2)
Since \(n = 4n – 3n\) is a difference of two integers, \(n\) is also an integer.
Conditions 1) and 2) are sufficient, when considered together.

Therefore, C is the answer.

Answer: C

If the original condition includes “1 variable”, or “2 variables and 1 equation”, or “3 variables and 2 equations” etc., one more equation is required to answer the question. If each of conditions 1) and 2) provide an additional equation, there is a 59% chance that D is the answer, a 38% chance that A or B is the answer, and a 3% chance that the answer is C or E. Thus, answer D (conditions 1) and 2), when applied separately, are sufficient to answer the question) is most likely, but there may be cases where the answer is A,B,C or E.

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

GMAT Club Bot
Re: Is n an integer? &nbs [#permalink] 19 Aug 2018, 17:43
Display posts from previous: Sort by

Is n an integer?

  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®.