Last visit was: 23 Apr 2026, 06:16 It is currently 23 Apr 2026, 06:16
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
Sub 505 (Easy)|   Algebra|   Inequalities|                           
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 23 Apr 2026
Posts: 109,778
Own Kudos:
810,776
 [40]
Given Kudos: 105,853
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,778
Kudos: 810,776
 [40]
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Oct 2016, 05:12
8
Kudos
Add Kudos
32
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

5% (low)

Question Stats:

82% (01:00) correct 18% (00:56) wrong based on 1880 sessions

History

Date
Time
Result
Not Attempted Yet
Is zw positive?

(1) z + w^3 = 20
(2) z is positive


DS12033
ShowHide Answer
Official Answer
E
Every tricky question should trigger a follow up quiz. Build that habit with GMAT Club Forum Quiz →.
User avatar
amu1093
User avatar
Joined: 24 Jun 2016
Last visit: 21 Jun 2017
Posts: 25
Own Kudos:
6
 [2]
Posts: 25
Kudos: 6
 [2]
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Oct 2016, 06:04
1
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Answer: E
(I)Because Z & W will take following different values..
+,+
+,-
-,+
-,- Besides that we Z & W will follow any value in form of integer and non integer.. Insufficient

(II)statement doesn't say anything about W
Insufficient

(I) &(II) still we have two cases of +,-
+,+
Gives two different value for zw
Hence insufficient

Sent from my MotoG3 using GMAT Club Forum mobile app
User avatar
acegmat123
User avatar
Joined: 28 Jun 2016
Last visit: 25 Oct 2021
Posts: 146
Own Kudos:
220
 [1]
Given Kudos: 99
Location: Canada
Concentration: Operations, Entrepreneurship
Posts: 146
Kudos: 220
 [1]
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Oct 2016, 07:42
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
amu1093
Answer: E
(I)Because Z & W will take following different values..
+,+
+,-
-,+
-,- Besides that we Z & W will follow any value in form of integer and non integer.. Insufficient

(II)statement doesn't say anything about W
Insufficient

(I) &(II) still we have two cases of +,-
+,+
Gives two different value for zw
Hence insufficient

Sent from my MotoG3 using GMAT Club Forum mobile app
Show more


-,- scenario is not possible as per statement 1. We don't have to bother about integer and non-integer scenarios since we are concerned about their signs.

But still answer is E.


Sent from my iPhone using GMAT Club Forum mobile app
avatar
Vinayak Shenoy
avatar
Joined: 06 Jun 2016
Last visit: 27 Jun 2017
Posts: 225
Own Kudos:
117
Given Kudos: 212
Location: India
Concentration: Operations, Strategy
Schools: ISB '18 (D)
GMAT 1: 600 Q49 V23
GMAT 2: 680 Q49 V34
GPA: 3.9
Schools: ISB '18 (D)
GMAT 2: 680 Q49 V34
Posts: 225
Kudos: 117
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Oct 2016, 08:24
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Is zw positive?

(1) z + w^3 = 20
(2) z is positive
Show more


IMO E

Statement 1 gives various possibilities Not Suff
Statement 2 doesn't tell anything about w. zw may or may not be positive Not Suff
Combining we still have 2 answers
Hence E
User avatar
AkshdeepS
User avatar
Joined: 13 Apr 2013
Last visit: 20 Apr 2026
Posts: 1,423
Own Kudos:
1,937
 [4]
Given Kudos: 1,002
Status:It's near - I can see.
Location: India
Concentration: International Business, Operations
GPA: 3.01
WE:Engineering (Real Estate)
Products:
My Reviews
Posts: 1,423
Kudos: 1,937
 [4]
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Oct 2016, 10:23
2
Kudos
Add Kudos
2
Bookmarks
Bookmark this Post
Bunuel
Is zw positive?

(1) z + w^3 = 20
(2) z is positive
Show more

Question: Is zw > 0.

For this to be true z & w must have the same sign.

Statement 1: z + w^3 = 20

If z = - 7 & w = 3, then -7 + 3^3 = 20 or 20 = 20, but answer to the question is NO (z*w not positive)

If z = 12 & w = 2, then 12 + 2^3 = 20 or 20 = 20, Answer to the question is YES (z*w positive)

Not sufficient

Statement 2:

No mention about the value of "w" so insufficient.

Combining 1 & 2

If z = 21 & w = -1, then 21 + (-1)^3 = 20 or 20 = 20, but answer to the question is NO (z*w not positive)

If z = 19 & w = 1, then 19 + (1)^3 = 20 or 20 = 20, Answer to the question is YES (z*w positive)

Answer (E)
User avatar
@p00rv@
User avatar
Joined: 02 Sep 2016
Last visit: 09 Feb 2017
Posts: 31
Own Kudos:
208
 [4]
Given Kudos: 130
Posts: 31
Kudos: 208
 [4]
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Oct 2016, 10:30
4
Kudos
Add Kudos
Bookmarks
Bookmark this Post
IMO answer must be E.
For example if we take the below cases which satisfy both the conditions given in A and B:
z=21,w=-1 --> z+w^3 =21-1 =20 But zw= -ve
z=19,w=1 --> z+w^3 =19+1 =20 But zw= +ve
i.e. we are not getting a definite answer. Hence E.
User avatar
amu1093
User avatar
Joined: 24 Jun 2016
Last visit: 21 Jun 2017
Posts: 25
Own Kudos:
6
Posts: 25
Kudos: 6
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Oct 2016, 22:38
Kudos
Add Kudos
Bookmarks
Bookmark this Post
@bunuel ooh yes.. -,- will finally yield +ve value.. True.. Thanks for feedback :)

Sent from my MotoG3 using GMAT Club Forum mobile app
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,974
Own Kudos:
8,710
 [3]
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert
Expert reply
Posts: 2,974
Kudos: 8,710
 [3]
Is zw positive? (1) z + w^3 = 20 (2) z is positive 07 Oct 2016, 12:01
2
Kudos
Add Kudos
1
Bookmarks
Bookmark this Post
Bunuel
Is zw positive?

(1) z + w^3 = 20
(2) z is positive
Show more

We need to determine whether the product of z and w is positive

Statement One Alone:

z + w^3 = 20

Using the information in statement one, we cannot determine whether the product of z and w is positive. For instance, if z = 12 and w = 2, the product of z and w is positive. However, if z = 28 and w = -2, then the product of z and w is negative. Statement one alone is not sufficient to answer the question. We can eliminate answer choices A and D.

Statement Two Alone:

z is positive

Using the information in statement two, we know that z is positive. However, since we don’t know anything about w, we cannot determine whether the product of z and w is positive. We can eliminate answer choice B.

Statements One and Two Together:

Using the information from statements one and two, we still cannot determine whether the product of z and w is positive. For instance, if z = 12 and w = 2, the product of z and w is positive. However, if z = 28 and w = -2, then the product of z and w is negative.

Answer: E
User avatar
MSIMBA
User avatar
Joined: 04 Jun 2017
Last visit: 14 Aug 2020
Posts: 73
Own Kudos:
40
Given Kudos: 180
Location: India
Concentration: Strategy, Operations
GMAT 1: 500 Q39 V20
GPA: 3.82
GMAT 1: 500 Q39 V20
Posts: 73
Kudos: 40
Is zw positive? (1) z + w^3 = 20 (2) z is positive 19 Jun 2019, 10:23
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Que, zw = + ve ?

1. z + w ^3 = 20
w = 1,2,3 ........ if w = 1 ^3 = 1 , 2^3 =8 , 3^3 = 27
if w = (-1)^3 = -1 , (-2) ^3 = -8
s0, zw can be +ve or -ve
not sufficient
2. z = +ve
w = 1,2,3 ........ if w = 1 ^3 = 1 , 2^3 =8 , 3^3 = 27
if w = (-1)^3 = -1 , (-2) ^3 = -8
zw can be +ve or -ve
not sufficient

E
User avatar
Basshead
User avatar
Joined: 09 Jan 2020
Last visit: 07 Feb 2024
Posts: 907
Own Kudos:
323
Given Kudos: 431
Location: United States
Posts: 907
Kudos: 323
Is zw positive? (1) z + w^3 = 20 (2) z is positive 06 Nov 2020, 05:31
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Is zw positive?

(1) \(z + w^3 = 20\)

If w = -4, then z is positive. zw = negative
If w = 2, then z is positive. zw = positive

INSUFFICIENT.

(2) z is positive

No information about w; INSUFFICIENT.

(1&2) \(z + w^3 = 20\); z is positive

w can still be negative or positive, resulting in two different scenarios. INSUFFICIENT.

Answer is E.
User avatar
MHIKER
User avatar
Joined: 14 Jul 2010
Last visit: 24 May 2021
Posts: 939
Own Kudos:
5,813
Given Kudos: 690
Status:No dream is too large, no dreamer is too small
Concentration: Accounting
Posts: 939
Kudos: 5,813
Is zw positive? (1) z + w^3 = 20 (2) z is positive 15 Dec 2020, 04:07
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Is zw positive?

(1) z + w^3 = 20
(2) z is positive
Show more


(1) \(12+(2)^3=20\); \(zw \) is positive

\(-7+(3)^3=20;\) \(zw \) is negative

Insufficient

(2) No information about \(w \) insufficient.

Considering both:
\(12+(2)^3=20;\) \(zw \) is positive

\(28+(-2)^3=20\); \(zw \) is negative

Insufficient.

The answer is E
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,957
Own Kudos:
1,117
Posts: 38,957
Kudos: 1,117
Is zw positive? (1) z + w^3 = 20 (2) z is positive 25 Sep 2025, 20:42
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109778 posts
kingbucky
498 posts
Gmat860sanskar
212 posts