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

 It is currently 23 Feb 2019, 09:10

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

Events & Promotions

Events & Promotions in February
PrevNext
SuMoTuWeThFrSa
272829303112
3456789
10111213141516
17181920212223
242526272812
Open Detailed Calendar
• FREE Quant Workshop by e-GMAT!

February 24, 2019

February 24, 2019

07:00 AM PST

09:00 AM PST

Get personalized insights on how to achieve your Target Quant Score.
• Free GMAT RC Webinar

February 23, 2019

February 23, 2019

07:00 AM PST

09:00 AM PST

Learn reading strategies that can help even non-voracious reader to master GMAT RC. Saturday, February 23rd at 7 AM PT

If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

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

Hide Tags

Manager
Joined: 11 Jun 2018
Posts: 67
GMAT 1: 500 Q39 V21
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

03 Feb 2019, 09:52
1
00:00

Difficulty:

85% (hard)

Question Stats:

10% (01:07) correct 90% (01:18) wrong based on 39 sessions

HideShow timer Statistics

If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.
VP
Joined: 09 Mar 2018
Posts: 1003
Location: India
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

03 Feb 2019, 10:14
1
Manat wrote:
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.

So

z can be even or fractions as well

1) X and Y are odd.

X^2−Y^3−2Z
Can be even or odd.

2) This doesn't tell anything about x and y

Lets combine both of them

X^2 - Y^3 - 2z

Will always be even - 2 * z

Even - Even

Even

Answers the question as a No

C
_________________

If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.

Math Expert
Joined: 02 Aug 2009
Posts: 7335
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

03 Feb 2019, 23:40
Manat wrote:
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.

$$X^2−Y^3−2Z$$

X, y and Z are non-zero numbers, so they can be fractions or integers...

(1) X and Y are odd.
$$x^2-Y^3$$ is surely even. Now it depends on 2Z..
say z is an integer ans is EVEN
say Z is a fraction, $$\frac{1}{2}$$, then ans is ODD
Insuff

(2) Z is even
Nothing about X and Y
insuff

Combined..
all are integers, so ans is always EVEN
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
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

GMAT Expert

Manager
Joined: 30 Oct 2018
Posts: 59
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

04 Feb 2019, 00:16
good question.. missed the part that z can also be a fraction and marked A
_________________

----------------------------------
Plz Kudos! if my post helps....

SVP
Joined: 18 Aug 2017
Posts: 1928
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

Updated on: 05 Feb 2019, 03:04
Manat wrote:
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.

#1
x& y are odd
X^2−Y^3−2Z ; would always be even ;
X^2−Y^3−2Z; would be odd only if z is even i.e "1/2 "fraction ;
insufficieint

#2
z even ; not sufficient , values of x,y not given

from 1&2
x & y are odd and z is even

so in that case X^2−Y^3−2Z would be odd if z is even fraction 1/2 and even when z is an integer..

IMO C
_________________

If you liked my solution then please give Kudos. Kudos encourage active discussions.

Originally posted by Archit3110 on 05 Feb 2019, 02:39.
Last edited by Archit3110 on 05 Feb 2019, 03:04, edited 1 time in total.
VP
Joined: 09 Mar 2018
Posts: 1003
Location: India
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

05 Feb 2019, 02:51
Archit3110 wrote:
Manat wrote:
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.

#1
x& y are odd
X^2−Y^3−2Z ; would always be even ;
X^2−Y^3−2Z; would be odd only if z is even i.e "1/2 "fraction ;
insufficieint

#2
z even ; not sufficient , values of x,y not given

from 1&2
x & y are odd and z is even

so in that case X^2−Y^3−2Z would be odd if z is even fraction 1/2 and even when z is an integer..

in #2 its given z is even ; it can be an integer or fraction as well...
X^2−Y^3−2Z
x & y are odd and z = 2 or even integer ; we would get even value
and
x& y are odd and z = 1/2 , we would get odd value
IMO E

Archit3110 but z = 1/2 is not even, because when you solve it, 0.5, is an odd fraction(non-zero number), this when used in statement A could have answered the question as Yes

That is why when we combine, it says that z is even

We could have taken 0.4 which is 2/5

odd -odd - 4/5
3-5 - 0.8
Even - Even
Even

Let me know what you think about this
_________________

If you notice any discrepancy in my reasoning, please let me know. Lets improve together.

Quote which i can relate to.
Many of life's failures happen with people who do not realize how close they were to success when they gave up.

SVP
Joined: 18 Aug 2017
Posts: 1928
Location: India
Concentration: Sustainability, Marketing
GPA: 4
WE: Marketing (Energy and Utilities)
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

05 Feb 2019, 03:03
KanishkM wrote:
Archit3110 wrote:
Manat wrote:
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.

#1
x& y are odd
X^2−Y^3−2Z ; would always be even ;
X^2−Y^3−2Z; would be odd only if z is even i.e "1/2 "fraction ;
insufficieint

#2
z even ; not sufficient , values of x,y not given

from 1&2
x & y are odd and z is even

so in that case X^2−Y^3−2Z would be odd if z is even fraction 1/2 and even when z is an integer..

in #2 its given z is even ; it can be an integer or fraction as well...
X^2−Y^3−2Z
x & y are odd and z = 2 or even integer ; we would get even value
and
x& y are odd and z = 1/2 , we would get odd value
IMO E

Archit3110 but z = 1/2 is not even, because when you solve it, 0.5, is an odd integer(non-zero number), this when used in statement A could have answered the question as Yes

That is why when we combine, it says that z is even

We could have taken 0.4 which is 2/5

odd -odd - 4/5
3-5 - 0.8
Even - Even
Even

Let me know what you think about this

KanishkM ; fractions cannot be even or odd ; only whole numbers can be categorised as even or odd..
I understood where i went wrong in my approach ; thanks..
_________________

If you liked my solution then please give Kudos. Kudos encourage active discussions.

Math Expert
Joined: 02 Aug 2009
Posts: 7335
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

05 Feb 2019, 03:26
KanishkM wrote:
Archit3110 wrote:
Manat wrote:
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.

#1
x& y are odd
X^2−Y^3−2Z ; would always be even ;
X^2−Y^3−2Z; would be odd only if z is even i.e "1/2 "fraction ;
insufficieint

#2
z even ; not sufficient , values of x,y not given

from 1&2
x & y are odd and z is even

so in that case X^2−Y^3−2Z would be odd if z is even fraction 1/2 and even when z is an integer..

in #2 its given z is even ; it can be an integer or fraction as well...
X^2−Y^3−2Z
x & y are odd and z = 2 or even integer ; we would get even value
and
x& y are odd and z = 1/2 , we would get odd value
IMO E

Archit3110 but z = 1/2 is not even, because when you solve it, 0.5, is an odd fraction(non-zero number), this when used in statement A could have answered the question as Yes

That is why when we combine, it says that z is even

We could have taken 0.4 which is 2/5

odd -odd - 4/5
3-5 - 0.8
Even - Even
Even

Let me know what you think about this

EVEN or ODD means they are integer also
_________________

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
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

GMAT Expert

Senior Manager
Joined: 17 Mar 2014
Posts: 439
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

05 Feb 2019, 20:18
KanishkM wrote:
Archit3110 wrote:
Manat wrote:
If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

(1) X and Y are odd.

(2) Z is even.

#1
x& y are odd
X^2−Y^3−2Z ; would always be even ;
X^2−Y^3−2Z; would be odd only if z is even i.e "1/2 "fraction ;
insufficieint

#2
z even ; not sufficient , values of x,y not given

from 1&2
x & y are odd and z is even

so in that case X^2−Y^3−2Z would be odd if z is even fraction 1/2 and even when z is an integer..

in #2 its given z is even ; it can be an integer or fraction as well...
X^2−Y^3−2Z
x & y are odd and z = 2 or even integer ; we would get even value
and
x& y are odd and z = 1/2 , we would get odd value
IMO E

Archit3110 but z = 1/2 is not even, because when you solve it, 0.5, is an odd fraction(non-zero number), this when used in statement A could have answered the question as Yes

That is why when we combine, it says that z is even

We could have taken 0.4 which is 2/5

odd -odd - 4/5
3-5 - 0.8
Even - Even
Even

Let me know what you think about this

Is EVEN or ODD mean INTEGER Only?

So 2.2 is not even fraction ?
Math Expert
Joined: 02 Sep 2009
Posts: 53066
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?  [#permalink]

Show Tags

05 Feb 2019, 20:40
ammuseeru wrote:
KanishkM wrote:
Archit3110 wrote:

#1
x& y are odd
X^2−Y^3−2Z ; would always be even ;
X^2−Y^3−2Z; would be odd only if z is even i.e "1/2 "fraction ;
insufficieint

#2
z even ; not sufficient , values of x,y not given

from 1&2
x & y are odd and z is even

so in that case X^2−Y^3−2Z would be odd if z is even fraction 1/2 and even when z is an integer..

in #2 its given z is even ; it can be an integer or fraction as well...
X^2−Y^3−2Z
x & y are odd and z = 2 or even integer ; we would get even value
and
x& y are odd and z = 1/2 , we would get odd value
IMO E

Archit3110 but z = 1/2 is not even, because when you solve it, 0.5, is an odd fraction(non-zero number), this when used in statement A could have answered the question as Yes

That is why when we combine, it says that z is even

We could have taken 0.4 which is 2/5

odd -odd - 4/5
3-5 - 0.8
Even - Even
Even

Let me know what you think about this

Is EVEN or ODD mean INTEGER Only?

So 2.2 is not even fraction ?

2.2 is NOT even or ODD.

Only integers can be even or odd:

An even number is an integer that is "evenly divisible" by 2, i.e., divisible by 2 without a remainder.

An odd number is an integer that is not evenly divisible by 2.
_________________
Re: If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?   [#permalink] 05 Feb 2019, 20:40
Display posts from previous: Sort by

If X, Y and Z are non-zero numbers, is X^2−Y^3−2Z odd?

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

 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®.