Last visit was: 18 Jul 2025, 16:40 It is currently 18 Jul 2025, 16:40
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
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 18 Jul 2025
Posts: 102,619
Own Kudos:
742,548
 [4]
Given Kudos: 98,235
Products:
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 102,619
Kudos: 742,548
 [4]
Kudos
Add Kudos
4
Bookmarks
Bookmark this Post
User avatar
IanStewart
User avatar
GMAT Tutor
Joined: 24 Jun 2008
Last visit: 18 Jul 2025
Posts: 4,145
Own Kudos:
Given Kudos: 98
 Q51  V47
Expert
Expert reply
Posts: 4,145
Kudos: 10,638
Kudos
Add Kudos
Bookmarks
Bookmark this Post
avatar
DaniyalAlwani
Joined: 29 Aug 2018
Last visit: 07 Nov 2020
Posts: 27
Own Kudos:
2
 [1]
Given Kudos: 23
Posts: 27
Kudos: 2
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
IanStewart
User avatar
GMAT Tutor
Joined: 24 Jun 2008
Last visit: 18 Jul 2025
Posts: 4,145
Own Kudos:
10,638
 [1]
Given Kudos: 98
 Q51  V47
Expert
Expert reply
Posts: 4,145
Kudos: 10,638
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
DaniyalAlwani
IanStewart

I know this question should be super easy but please explain when I went wrong.

Target question: Possible values of x: 0<=x<=1

Statement 1: 1<=x<=3
0 is not part of this; hence false

Statement 2: -1<=x<=2
Both 0 and 1 are part of this range, hence B should be the answer.

Please, correct me if I am wrong.

I think there are two things wrong with your approach. First, I believe you're assuming x is an integer, and in pure algebra questions, you should never assume (unless told) that your unknowns are integers. It's possible, using Statement 1, that x = 2.5, for example.

But it also appears that you're approaching the question 'backwards', if I understand correctly how you solved. It seems to me you assumed x was either 0 or 1, and then tested whether each Statement was true. That's doing things the wrong way around. In DS, the Statements are facts. They cannot be wrong, so you never want to test whether a Statement is true -- the Statements are automatically true. It's the question itself that we don't know the answer to. So here, we aren't sure, before using the Statements, if x is between -1 and 2. When we look at Statement 2 alone, we know for an absolute fact that x is between -2 and 3, but that's all we know. So it's possible that x = 1, say, and then the answer to the question "Is -1 < x < 2?" is "yes". But it's also possible that x = 2.5, or x = -1.5, and then the answer to the question "Is -1 < x < 2?" is "no". Since we can get two different answers to the question, "yes" and "no", Statement 2 is not sufficient alone. And as in my post above, even using both Statements we can't be certain x is between -1 and 2, so the answer is E.
User avatar
TestPrepUnlimited
Joined: 17 Sep 2014
Last visit: 30 Jun 2022
Posts: 1,226
Own Kudos:
Given Kudos: 6
Location: United States
GMAT 1: 780 Q51 V45
GRE 1: Q170 V167
Expert
Expert reply
GMAT 1: 780 Q51 V45
GRE 1: Q170 V167
Posts: 1,226
Kudos: 1,067
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Bunuel
Is \(-1 < x < 2\) ?


(1) \(0 < x < 4\)

(2) \(-2 < x < 3\)



DS21188

We need the range to be within -1 < x < 2 for sufficiency.

Statement 1:
We can select x = 1 or x = 3.5, x = 1 would be within (-1, 2) but x = 3.5 would be outside. Insufficient.

Statement 2:
We can select x = 1 or x = -1.5, x = 1 would be within (-1, 2) but x = -1.5 would be outside. Insufficient.

Combined:
Combined we can reduce the range to 0 < x < 3. However, this does not fully incorporate -1 < x < 2 so this is insufficient. E.g. x = 2.5 is outside of range.

Ans: E
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 37,455
Own Kudos:
Posts: 37,455
Kudos: 1,013
Kudos
Add Kudos
Bookmarks
Bookmark this Post
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.
Moderators:
Math Expert
102619 posts
454 posts