Last visit was: 19 Nov 2025, 08:08 It is currently 19 Nov 2025, 08:08
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
User avatar
suk1234
Joined: 29 Sep 2013
Last visit: 04 Jul 2016
Posts: 37
Own Kudos:
185
 [15]
Given Kudos: 48
Posts: 37
Kudos: 185
 [15]
3
Kudos
Add Kudos
12
Bookmarks
Bookmark this Post
User avatar
mikemcgarry
User avatar
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Last visit: 06 Aug 2018
Posts: 4,479
Own Kudos:
30,536
 [4]
Given Kudos: 130
Expert
Expert reply
Posts: 4,479
Kudos: 30,536
 [4]
2
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
User avatar
suk1234
Joined: 29 Sep 2013
Last visit: 04 Jul 2016
Posts: 37
Own Kudos:
Given Kudos: 48
Posts: 37
Kudos: 185
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
mikemcgarry
User avatar
Magoosh GMAT Instructor
Joined: 28 Dec 2011
Last visit: 06 Aug 2018
Posts: 4,479
Own Kudos:
30,536
 [3]
Given Kudos: 130
Expert
Expert reply
Posts: 4,479
Kudos: 30,536
 [3]
2
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
suk1234
Thank you Mike for the Quick rescue!

Here is how I evaluated Statement 1:

Z=1 and Either X=0 or Y=0 or Both X and Y = 0

Then evaluate all the possible values!
1. (X=0) 0*Y*1=0
2. (Y=0) X*0*1=0
3. (X and Y = 0) 0*0*1=0

I think in case of statement 2 this reasoning doesn't apply because it presents three cases which may or may not be true ( \(x=0,\) or \(y=0\) or \(z=1\) either of these can happen or not).
But in case of statement 1 we are definitely sure about the value of XY.
Dear suk1234
I'm happy to respond. :-)

Statement #1 says
xyz - xy = 0
Add xy to both sides:
xyz = xy
(xy)*z = (xy)

Here, we are presented with a choice.
Case One:
If (xy) does not equal zero, then we can divide by (xy), and get z = 1. That's one case, in which (xy) can have any value on the number line other than zero, and z = 1. Here, the product xyz would be equal to xy, and could be anything other than zero.
Case Two:
If (xy) = 0, then z could be anything on the number line. This is the other case. If (xy) = 0, then either x = 0 or y = 0, which will make the product equal zero. (Here, z could be 1, or it could be anything else on the number line.)

You see, the crucial mathematical word is the word "or" ---- either z = 1 OR (xy) = 0. You are interpreting the two requirements as if they are simultaneous, not a mutually exclusive choice. The two cases are actually mutually exclusive.

Does all this make sense?
Mike :-)
User avatar
suk1234
Joined: 29 Sep 2013
Last visit: 04 Jul 2016
Posts: 37
Own Kudos:
Given Kudos: 48
Posts: 37
Kudos: 185
Kudos
Add Kudos
Bookmarks
Bookmark this Post
mikemcgarry
suk1234
Thank you Mike for the Quick rescue!

Here is how I evaluated Statement 1:

Z=1 and Either X=0 or Y=0 or Both X and Y = 0

Then evaluate all the possible values!
1. (X=0) 0*Y*1=0
2. (Y=0) X*0*1=0
3. (X and Y = 0) 0*0*1=0

I think in case of statement 2 this reasoning doesn't apply because it presents three cases which may or may not be true ( \(x=0,\) or \(y=0\) or \(z=1\) either of these can happen or not).
But in case of statement 1 we are definitely sure about the value of XY.
Dear suk1234
I'm happy to respond. :-)

Statement #1 says
xyz - xy = 0
Add xy to both sides:
xyz = xy
(xy)*z = (xy)

Here, we are presented with a choice.
Case One:
If (xy) does not equal zero, then we can divide by (xy), and get z = 1. That's one case, in which (xy) can have any value on the number line other than zero, and z = 1. Here, the product xyz would be equal to xy, and could be anything other than zero.
Case Two:
If (xy) = 0, then z could be anything on the number line. This is the other case. If (xy) = 0, then either x = 0 or y = 0, which will make the product equal zero. (Here, z could be 1, or it could be anything else on the number line.)

You see, the crucial mathematical word is the word "or" ---- either z = 1 OR (xy) = 0. You are interpreting the two requirements as if they are simultaneous, not a mutually exclusive choice. The two cases are actually mutually exclusive.

Does all this make sense?
Mike :-)
Oh I see, where I was going wrong with it.Thank Mike that was an amazing explanation.
User avatar
Temurkhon
Joined: 23 Jan 2013
Last visit: 06 Apr 2019
Posts: 412
Own Kudos:
Given Kudos: 43
Schools: Cambridge'16
Schools: Cambridge'16
Posts: 412
Kudos: 314
Kudos
Add Kudos
Bookmarks
Bookmark this Post
xyz=?

St.1 xyz-xy=0 => xy(z-1)=0, so xy=0 or z=1 or both . If xy=0, xyz=0, if z=1, not clear. INSUFF.

St.2 Either x = 0, or y = 0 or z = 1. Again if z=1, not clear. INSUFF.

St1+St2 tell the same, so INSUFF

E
User avatar
chetan86
Joined: 17 Oct 2012
Last visit: 22 Dec 2024
Posts: 55
Own Kudos:
Given Kudos: 53
Location: India
Concentration: Strategy, Finance
WE:Information Technology (Computer Software)
Posts: 55
Kudos: 641
Kudos
Add Kudos
Bookmarks
Bookmark this Post
what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0 or z=1
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 15 Nov 2025
Posts: 11,238
Own Kudos:
43,703
 [3]
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,238
Kudos: 43,703
 [3]
2
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
chetan86
what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0


Hi,
you will have to relook into OA or the typo erros ..

(1) \(xyz-xy=0\)..
\(xy(z-1) = 0...\)
either z=1 or xy = 0...
if z=1 and xy is NOT equal to 0.. xyz can be any non-zero integer depending on xy..
If xy =0, ans will be 0..
Insuff

(2) Either x=0 or y=0
In any case , xyz will be 0..
Suff

B..

NOTE - Pl Check before posting and post correctly.
Merging topics
User avatar
chetan86
Joined: 17 Oct 2012
Last visit: 22 Dec 2024
Posts: 55
Own Kudos:
641
 [1]
Given Kudos: 53
Location: India
Concentration: Strategy, Finance
WE:Information Technology (Computer Software)
Posts: 55
Kudos: 641
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Yeah, I rechecked the answer, and it is E. Even I am confused about this question so thought to post this question to clear my understandings.
This question is from Advance GMAT Quant.

OE is :
We can test different numeric scenarios for x, y and z using Scenario Charts. Statement (1) tells us that xyz – xy = 0. First, let's factor the equation:
xyz – xy = 0
xy(z – 1) = 0
For this product to equal zero, either x = 0, or y = 0, or z = 1.

Thus if x = 0 or y = 0, then xyz = 0, but if z = 1, then xyz could take on any value. INSUFFICIENT.

Statement (2) tells us that either x = 0 or y = 0 or z = 1. This is the exact same information from Statement (1), so we can eliminate A, B and C by Spotting Identical Statements. Since Statement (1) also proved to be insufficient, we can eliminate D as well.

The correct answer is E.

chetan2u
chetan86
what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0


Hi,
you will have to relook into OA or the typo erros ..

(1) \(xyz-xy=0\)..
\(xy(z-1) = 0...\)
either z=1 or xy = 0...
if z=1 and xy is NOT equal to 0.. xyz can be any non-zero integer depending on xy..
If xy =0, ans will be 0..
Insuff

(2) Either x=0 or y=0
In any case , xyz will be 0..
Suff

B..
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 15 Nov 2025
Posts: 11,238
Own Kudos:
43,703
 [1]
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,238
Kudos: 43,703
 [1]
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
chetan86
Yeah, I rechecked the answer, and it is E. Even I am confused about this question so thought to post this question to clear my understandings.
This question is from Advance GMAT Quant.

OE is :
We can test different numeric scenarios for x, y and z using Scenario Charts. Statement (1) tells us that xyz – xy = 0. First, let's factor the equation:
xyz – xy = 0
xy(z – 1) = 0
For this product to equal zero, either x = 0, or y = 0, or z = 1.

Thus if x = 0 or y = 0, then xyz = 0, but if z = 1, then xyz could take on any value. INSUFFICIENT.

Statement (2) tells us that either x = 0 or y = 0 or z = 1. This is the exact same information from Statement (1), so we can eliminate A, B and C by Spotting Identical Statements. Since Statement (1) also proved to be insufficient, we can eliminate D as well.

The correct answer is E.

chetan2u
chetan86
what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0


Hi,
you will have to relook into OA or the typo erros ..

(1) \(xyz-xy=0\)..
\(xy(z-1) = 0...\)
either z=1 or xy = 0...
if z=1 and xy is NOT equal to 0.. xyz can be any non-zero integer depending on xy..
If xy =0, ans will be 0..
Insuff

(2) Either x=0 or y=0
In any case , xyz will be 0..
Suff

B..

Then there is a error in what you have given as statement 2 and what is mentioned..
as per your Q.. II is "Either x=0 or y=0", whereas the source is giveing in the OE as "Statement (2) tells us that either x = 0 or y = 0 or z = 1"..

Both the statements do NOT mean the same ..
and if statement is - Statement (2) tells us that either x = 0 or y = 0 or z = 1.. ANS will be E
User avatar
chetan86
Joined: 17 Oct 2012
Last visit: 22 Dec 2024
Posts: 55
Own Kudos:
Given Kudos: 53
Location: India
Concentration: Strategy, Finance
WE:Information Technology (Computer Software)
Posts: 55
Kudos: 641
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u


Then there is a error in what you have given as statement 2 and what is mentioned..
as per your Q.. II is "Either x=0 or y=0", whereas the source is giveing in the OE as "Statement (2) tells us that either x = 0 or y = 0 or z = 1"..

Both the statements do NOT mean the same ..
and if statement is - Statement (2) tells us that either x = 0 or y = 0 or z = 1.. ANS will be E

I have updated the question. Thanks!!
User avatar
Himanshu9818
Joined: 13 Apr 2016
Last visit: 22 Feb 2017
Posts: 46
Own Kudos:
Given Kudos: 7
Location: India
GMAT 1: 640 Q50 V27
GPA: 3
WE:Operations (Hospitality and Tourism)
GMAT 1: 640 Q50 V27
Posts: 46
Kudos: 126
Kudos
Add Kudos
Bookmarks
Bookmark this Post
[quote="chetan86"]what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0 or z=1

I think the answer has to be E because none of the statement is giving any fix value for any of the variable and also by combining we are not getting any confirmed answer.
User avatar
chetan86
Joined: 17 Oct 2012
Last visit: 22 Dec 2024
Posts: 55
Own Kudos:
Given Kudos: 53
Location: India
Concentration: Strategy, Finance
WE:Information Technology (Computer Software)
Posts: 55
Kudos: 641
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Below explanation resolved my doubts. Thanks!!

mikemcgarry
suk1234
Thank you Mike for the Quick rescue!

Here is how I evaluated Statement 1:

Z=1 and Either X=0 or Y=0 or Both X and Y = 0

Then evaluate all the possible values!
1. (X=0) 0*Y*1=0
2. (Y=0) X*0*1=0
3. (X and Y = 0) 0*0*1=0

I think in case of statement 2 this reasoning doesn't apply because it presents three cases which may or may not be true ( \(x=0,\) or \(y=0\) or \(z=1\) either of these can happen or not).
But in case of statement 1 we are definitely sure about the value of XY.
Dear suk1234
I'm happy to respond. :-)

Statement #1 says
xyz - xy = 0
Add xy to both sides:
xyz = xy
(xy)*z = (xy)

Here, we are presented with a choice.
Case One:
If (xy) does not equal zero, then we can divide by (xy), and get z = 1. That's one case, in which (xy) can have any value on the number line other than zero, and z = 1. Here, the product xyz would be equal to xy, and could be anything other than zero.
Case Two:
If (xy) = 0, then z could be anything on the number line. This is the other case. If (xy) = 0, then either x = 0 or y = 0, which will make the product equal zero. (Here, z could be 1, or it could be anything else on the number line.)

You see, the crucial mathematical word is the word "or" ---- either z = 1 OR (xy) = 0. You are interpreting the two requirements as if they are simultaneous, not a mutually exclusive choice. The two cases are actually mutually exclusive.

Does all this make sense?
Mike :-)
User avatar
Gauravji21
Joined: 27 Aug 2020
Last visit: 25 Jan 2024
Posts: 82
Own Kudos:
Given Kudos: 21
Posts: 82
Kudos: 45
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u
chetan86
what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0


Hi,
you will have to relook into OA or the typo erros ..

(1) \(xyz-xy=0\)..
\(xy(z-1) = 0...\)
either z=1 or xy = 0...
if z=1 and xy is NOT equal to 0.. xyz can be any non-zero integer depending on xy..
If xy =0, ans will be 0..
Insuff

(2) Either x=0 or y=0
In any case , xyz will be 0..
Suff

B..

NOTE - Pl Check before posting and post correctly.
Merging topics


chetan nick
1) Can you elaborate on difference between Either x=0 or y=0 and xy = 0. You said in an answer that both statements are not same.

2) Also, in xy (z-1) = 0. Either xy=0 or Z=1
A)Taking z=1,putting value of z in the equation we get xy=0
so, xyz will be = (0) x 1 = 0
Whatever will be the value of xy, the product will be zero.

B) Similarly, Taking xy=0, xyz=0 whatever be the value of z

Could you please tell what is wrong with the above concept ?
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 15 Nov 2025
Posts: 11,238
Own Kudos:
43,703
 [1]
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,238
Kudos: 43,703
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Gauravji21
chetan2u
chetan86
what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0


Hi,
you will have to relook into OA or the typo erros ..

(1) \(xyz-xy=0\)..
\(xy(z-1) = 0...\)
either z=1 or xy = 0...
if z=1 and xy is NOT equal to 0.. xyz can be any non-zero integer depending on xy..
If xy =0, ans will be 0..
Insuff

(2) Either x=0 or y=0
In any case , xyz will be 0..
Suff

B..

NOTE - Pl Check before posting and post correctly.
Merging topics


chetan nick
1) Can you elaborate on difference between Either x=0 or y=0 and xy = 0. You said in an answer that both statements are not same.

2) Also, in xy (z-1) = 0. Either xy=0 or Z=1
A)Taking z=1,putting value of z in the equation we get xy=0
so, xyz will be = (0) x 1 = 0
Whatever will be the value of xy, the product will be zero.

B) Similarly, Taking xy=0, xyz=0 whatever be the value of z

Could you please tell what is wrong with the above concept ?


Hi

1) When xy=0, we cannot be sure what is 0, but at least one of the x and y is surely 0. That is why either x=0 or y=0 or both x and y are 0.
2) xy(z-1)=0...
When z=1, xy(1-1)=xy*0=0, so xy can be 0,10,100 as (anything)*0=0
User avatar
Gauravji21
Joined: 27 Aug 2020
Last visit: 25 Jan 2024
Posts: 82
Own Kudos:
Given Kudos: 21
Posts: 82
Kudos: 45
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u
Gauravji21
chetan2u
chetan86
what is the value of xyz?
(1) xyz-xy=0
(2) Either x=0 or y=0


Hi,
you will have to relook into OA or the typo erros ..

(1) \(xyz-xy=0\)..
\(xy(z-1) = 0...\)
either z=1 or xy = 0...
if z=1 and xy is NOT equal to 0.. xyz can be any non-zero integer depending on xy..
If xy =0, ans will be 0..
Insuff

(2) Either x=0 or y=0
In any case , xyz will be 0..
Suff

B..

NOTE - Pl Check before posting and post correctly.
Merging topics


chetan nick
1) Can you elaborate on difference between Either x=0 or y=0 and xy = 0. You said in an answer that both statements are not same.

2) Also, in xy (z-1) = 0. Either xy=0 or Z=1
A)Taking z=1,putting value of z in the equation we get xy=0
so, xyz will be = (0) x 1 = 0
Whatever will be the value of xy, the product will be zero.

B) Similarly, Taking xy=0, xyz=0 whatever be the value of z

Could you please tell what is wrong with the above concept ?


Hi

1) When xy=0, we cannot be sure what is 0, but at least one of the x and y is surely 0. That is why either x=0 or y=0 or both x and y are 0.
2) xy(z-1)=0...
When z=1, xy(1-1)=xy*0=0, so xy can be 0,10,100 as (anything)*0=0

Thanks for your reply Chetan.
But my question is why should we be concerned about specific values of X and Y. Whatever be the value of X & Y, we need to find the product of x, y & z i.e. xyz = ?

We have value of XY and Z and hence we can find the value of xyz. ?

Posted from my mobile device
User avatar
Gauravji21
Joined: 27 Aug 2020
Last visit: 25 Jan 2024
Posts: 82
Own Kudos:
Given Kudos: 21
Posts: 82
Kudos: 45
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Any clarification on my doubt chetan.

Posted from my mobile device
User avatar
chetan2u
User avatar
GMAT Expert
Joined: 02 Aug 2009
Last visit: 15 Nov 2025
Posts: 11,238
Own Kudos:
Given Kudos: 335
Status:Math and DI Expert
Location: India
Concentration: Human Resources, General Management
GMAT Focus 1: 735 Q90 V89 DI81
Products:
Expert
Expert reply
GMAT Focus 1: 735 Q90 V89 DI81
Posts: 11,238
Kudos: 43,703
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Gauravji21
Any clarification on my doubt chetan.

Posted from my mobile device


Hi

I am sorry but I have not understood how you have got the values of xy and z.
Statement II tells you either xy=0 or z=1
xy=0.....xyz will be 0 irrespective of value of z
z=1....xyz will depend on xy and we cannot say what is xy. If xy =0, xyz =0, but if xy=7, xyz=7
User avatar
Gauravji21
Joined: 27 Aug 2020
Last visit: 25 Jan 2024
Posts: 82
Own Kudos:
Given Kudos: 21
Posts: 82
Kudos: 45
Kudos
Add Kudos
Bookmarks
Bookmark this Post
chetan2u
Gauravji21
Any clarification on my doubt chetan.

Posted from my mobile device


Hi

I am sorry but I have not understood how you have got the values of xy and z.
Statement II tells you either xy=0 or z=1
xy=0.....xyz will be 0 irrespective of value of z
z=1....xyz will depend on xy and we cannot say what is xy. If xy =0, xyz =0, but if xy=7, xyz=7

Hi Chetan
Thanks for your reply. I was doing it in a wrong way. I was actually putting value of Z=1 in the equation xy(z−1)=0 whereas I was supposed to put the value so obtained from St1 equation in equation in question stem i.e. xyz = 0.
User avatar
Ankit__7182
Joined: 02 Mar 2024
Last visit: 29 Jun 2025
Posts: 56
Own Kudos:
Given Kudos: 88
GMAT Focus 1: 645 Q84 V82 DI79
Products:
GMAT Focus 1: 645 Q84 V82 DI79
Posts: 56
Kudos: 34
Kudos
Add Kudos
Bookmarks
Bookmark this Post
From S1, we get xyz =xy (Insufficient)
From S2 we can find xyz =0 only if x=0 or y=0 but if z=0 then xyz =xy (Insufficient)
see from both statements together also we are unable to get any value of xyz, coz both ends in same result xyz=xy
Moderators:
Math Expert
105389 posts
496 posts