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

 It is currently 24 Jan 2019, 00:41

### 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 January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
• ### Key Strategies to Master GMAT SC

January 26, 2019

January 26, 2019

07:00 AM PST

09:00 AM PST

Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.
• ### Free GMAT Number Properties Webinar

January 27, 2019

January 27, 2019

07:00 AM PST

09:00 AM PST

Attend this webinar to learn a structured approach to solve 700+ Number Properties question in less than 2 minutes.

# Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 52442
Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

09 Jan 2018, 22:32
00:00

Difficulty:

45% (medium)

Question Stats:

50% (01:12) correct 50% (01:23) wrong based on 42 sessions

### HideShow timer Statistics

Is x an integer?

(1) The average (arithmetic mean) of x – 1 and x + 1 is an integer.
(2) The average (arithmetic mean) of x and –x is an integer.

_________________
DS Forum Moderator
Joined: 21 Aug 2013
Posts: 1435
Location: India
Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

09 Jan 2018, 23:11
Bunuel wrote:
Is x an integer?

(1) The average (arithmetic mean) of x – 1 and x + 1 is an integer.
(2) The average (arithmetic mean) of x and –x is an integer.

(1) Average of x-1 and x+1 is = (x-1 + x+1)/2 = 2x/2 = x, which is given to be an integer. So x is an integer. Sufficient.

(2) Average of x and -x is = (x - x)/2 = 0/2 = 0. Whatever be the value of x (integer or non-integer), sum of x and -x will always be 0, and thus average will also be 0. So we cant say whether x is an integer or not based on this information. Insufficient.

Intern
Joined: 09 Jul 2017
Posts: 27
Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

10 Jan 2018, 10:43
X could be a decimal also right ? Will A be the sufficient answer ?

Sent from my iPhone using GMAT Club Forum
Director
Joined: 31 Jul 2017
Posts: 518
Location: Malaysia
GMAT 1: 700 Q50 V33
GPA: 3.95
WE: Consulting (Energy and Utilities)
Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

10 Jan 2018, 19:37
Bunuel wrote:
Is x an integer?

(1) The average (arithmetic mean) of x – 1 and x + 1 is an integer.
(2) The average (arithmetic mean) of x and –x is an integer.

Stmnt 1: Let X = 1.. we get average as Integer, let x = 1/2 we get average as Integer.. So not suffiecient.
Stmn 2: X = 1, Average Integer... X = 1/2, Average = Integer

So E.
_________________

If my Post helps you in Gaining Knowledge, Help me with KUDOS.. !!

Intern
Joined: 22 Nov 2017
Posts: 25
Location: United States
Concentration: Technology, Healthcare
Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

10 Jan 2018, 20:12
Average of x-1 and x+1 is X which is given to be an integer so X is an integer so sufficient. Statement 2 the average is 0 which does not give any idea abt X. So not sufficient. So answer is A.

Sent from my SAMSUNG-SM-J120A using GMAT Club Forum mobile app
Math Expert
Joined: 02 Aug 2009
Posts: 7215
Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

10 Jan 2018, 20:30
rahul16singh28 wrote:
Bunuel wrote:
Is x an integer?

(1) The average (arithmetic mean) of x – 1 and x + 1 is an integer.
(2) The average (arithmetic mean) of x and –x is an integer.

Stmnt 1: Let X = 1.. we get average as Integer, let x = 1/2 we get average as Integer.. So not suffiecient.
Stmn 2: X = 1, Average Integer... X = 1/2, Average = Integer

So E.

I
Average of x-1 and x+1 is nothing but x itself and it is given as integer, so x is integer..
average of x-1 and x+1 is $$\frac{x-1+x+1}{2}=\frac{2x}{2}=x$$
so statement I is suff..

II
Whatever be value of x, the average of x and -x should be 0
so statement II does not tell anything new
insuff

A
_________________

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

Intern
Joined: 22 Nov 2017
Posts: 25
Location: United States
Concentration: Technology, Healthcare
Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

10 Jan 2018, 20:38
Average is 0 in statement 2 and not the value of x. X can be integer or non integer the average of X and -x is always 0. So it doesnt say the type of X

Sent from my SAMSUNG-SM-J120A using GMAT Club Forum mobile app
DS Forum Moderator
Joined: 21 Aug 2013
Posts: 1435
Location: India
Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x +  [#permalink]

### Show Tags

10 Jan 2018, 21:43
akhilbatra06 wrote:
Zero is an integer

Sent from my iPhone using GMAT Club Forum

Hi

Yes, zero is an integer. So average of x and -x will be 0, which is an integer. If x=2, then also average of x and -x is zero. If x=1.5, then also average of x and -x is zero.
So zero being an integer doesnt tell us anything whether x will be an integer or not. '

Re: Is x an integer? (1) The average (arithmetic mean) of x – 1 and x + &nbs [#permalink] 10 Jan 2018, 21:43
Display posts from previous: Sort by