Is x + y – z + t even? : GMAT Data Sufficiency (DS)
Check GMAT Club Decision Tracker for the Latest School Decision Releases https://gmatclub.com/AppTrack

 It is currently 26 Feb 2017, 08:54

### 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 x + y – z + t even?

Author Message
TAGS:

### Hide Tags

Intern
Joined: 04 Mar 2012
Posts: 46
Followers: 0

Kudos [?]: 225 [0], given: 10

Is x + y – z + t even? [#permalink]

### Show Tags

22 May 2012, 08:12
3
This post was
BOOKMARKED
00:00

Difficulty:

65% (hard)

Question Stats:

52% (01:59) correct 48% (01:14) wrong based on 152 sessions

### HideShow timer Statistics

Is $$x + y – z + t$$ even?

(1) $$x + y + t$$ is even
(2) $$t*z$$ is odd
[Reveal] Spoiler: OA

Last edited by stonecold on 29 Dec 2016, 14:50, edited 2 times in total.
Edited the question.
Manager
Status: I will not stop until i realise my goal which is my dream too
Joined: 25 Feb 2010
Posts: 235
Schools: Johnson '15
Followers: 2

Kudos [?]: 50 [0], given: 16

Re: Is x + y – z + t even? [#permalink]

### Show Tags

22 May 2012, 08:35
1
This post was
BOOKMARKED
gmihir wrote:
Is x + y – z + t even?
(1) x + y + t is even
(2) tz is odd

why the answer is not C? as tz is odd, t and z both must be odd and and as x+y+t is even, even - odd = odd so C, can anyone please explain?

Though i did not understand why the OA is E

i would go through my understanding, and SME can help me out here

given that x + y + t - z is even
so for this
two terms (x + y + t) & z
so to have a even result both the terms should be either even or both should be odd

E - E = E
O - O = E

1) info about x + y + t is even .. good for us, but no information about z is given , hence INSUFFICIENT

2) tz is odd

O * O = O
E * O = O
O * E = O

hence we cannot make sure if z is even or ODD, hence INSUFFICIENT

so the answer choices A, B, D are knocked off...

now taking together 1 & 2

x + y + t = even
and z is either even or odd
_________________

Regards,
Harsha

Note: Give me kudos if my approach is right , else help me understand where i am missing.. I want to bell the GMAT Cat

Satyameva Jayate - Truth alone triumphs

Math Expert
Joined: 02 Sep 2009
Posts: 37131
Followers: 7260

Kudos [?]: 96686 [3] , given: 10776

Re: Is x + y – z + t even? [#permalink]

### Show Tags

22 May 2012, 09:51
3
KUDOS
Expert's post
2
This post was
BOOKMARKED
gmihir wrote:
Is x + y – z + t even?

(1) x + y + t is even
(2) tz is odd

why the answer is not C? as tz is odd, t and z both must be odd and and as x+y+t is even, even - odd = odd so C, can anyone please explain?

Notice that we are not told that unknowns can only be integers.

Even when we consider the statements together we can have the following cases:
$$x+y=odd$$, $$t=odd$$ and $$z=odd$$ then $$(x+y)-z+t=odd-odd+odd=odd$$ and the answer to the question is NO;
$$x+y=\frac{3}{2}$$, $$t=\frac{1}{2}$$ and $$z=2$$ then $$(x+y)-z+t=\frac{3}{2}-2+\frac{1}{2}=0=even$$ and the answer to the question is YES.

Hope it's clear.
_________________
Senior Manager
Joined: 28 Dec 2010
Posts: 334
Location: India
Followers: 1

Kudos [?]: 208 [1] , given: 33

Re: Is x + y – z + t even? [#permalink]

### Show Tags

22 May 2012, 19:26
1
KUDOS
Picked E. because we are not told that all digits are integers. So in that case it the the ans may not be an integer. And if it is not an integer it is also neither even nor odd.
Intern
Joined: 30 Mar 2012
Posts: 36
Followers: 0

Kudos [?]: 2 [0], given: 11

Re: Is x + y – z + t even? [#permalink]

### Show Tags

24 May 2012, 06:51
harshavmrg wrote:
E * O = O
O * E = O

This is wrong.
Going by examples when you multiply the even(4)with the odd(3) the answer is 12 which is even.

hence whenever a Even is multiplied to a even or odd number it is always an even number. I hope you take note of this point.

Bunuel wrote:
Notice that we are not told that unknowns can only be integers.

This is one of the first points to try in such questions when nothing is mentioned about the type of numbers.
_________________

This time its personal..

Joined: 28 Mar 2012
Posts: 321
Location: India
GMAT 1: 640 Q50 V26
GMAT 2: 660 Q50 V28
GMAT 3: 730 Q50 V38
Followers: 29

Kudos [?]: 406 [0], given: 23

Re: Is x + y – z + t even? [#permalink]

### Show Tags

24 May 2012, 19:24
gmihir wrote:
Is x + y – z + t even?

(1) x + y + t is even
(2) tz is odd

why the answer is not C? as tz is odd, t and z both must be odd and and as x+y+t is even, even - odd = odd so C, can anyone please explain?

Hi,

Whenever you are trying to solve such type of question, do not direct assume all variables as integers (if it is not mentioned).

x,y,z & t can be any real number for which the above relationships are true.

Regards,
Senior Manager
Joined: 28 Dec 2010
Posts: 334
Location: India
Followers: 1

Kudos [?]: 208 [0], given: 33

Re: Is x + y – z + t even? [#permalink]

### Show Tags

24 May 2012, 20:18
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13975
Followers: 591

Kudos [?]: 167 [0], given: 0

Re: Is x + y – z + t even? [#permalink]

### Show Tags

29 Jul 2014, 11:14
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Manager
Joined: 29 May 2013
Posts: 94
GMAT 1: 710 Q49 V38
GPA: 4
Followers: 2

Kudos [?]: 5 [0], given: 51

Re: Is x + y – z + t even? [#permalink]

### Show Tags

29 Jul 2014, 14:54
gmihir wrote:
Is x + y – z + t even?

(1) x + y + t is even
(2) tz is odd

why the answer is not C? as tz is odd, t and z both must be odd and and as x+y+t is even, even - odd = odd so C, can anyone please explain?

The question does not say that x,y,z,t are integers. They can be fraction also.
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 13975
Followers: 591

Kudos [?]: 167 [0], given: 0

Re: Is x + y – z + t even? [#permalink]

### Show Tags

22 Nov 2016, 04:59
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Re: Is x + y – z + t even?   [#permalink] 22 Nov 2016, 04:59
Similar topics Replies Last post
Similar
Topics:
2 If, x, y, and z are integers, is x even? 6 23 Jun 2015, 01:47
12 If y is an integer and x + y + z is odd, is y even? 16 18 Feb 2015, 03:45
7 If x, y, and z are all positive integers, is x + y + z even? 2 22 Oct 2013, 07:07
5 The product of integers x, y, and z is even, is z even? 4 03 Apr 2012, 00:54
3 x+y+z is even, is x*y*z even? 8 16 Jun 2010, 21:50
Display posts from previous: Sort by