|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
65%
(hard)
Question Stats:
60% (02:17) correct
40%
(02:37)
wrong
based on 221
sessions
History
Date
Time
Result
Not Attempted Yet
If ac/(db) < 0, is d – b < 0 ?
(1) |a − c| = |a| − |c|
(2) d – b > d + b
_________________
(1) |a − c| = |a| − |c|
(2) d – b > d + b
Pure algebraic questions like this one are no longer part of the GMAT Data Sufficiency syllabus.
For relevant Data Sufficiency questions, please check the Data Sufficiency forum:
Data Sufficiency Forum
Data Sufficiency Forum
_________________
New to the GMAT Club?
- • Questions: Question Bank | Bunuel's Signature Collection
• Tests: GMAT Club Tests | Forum Quiz
• Guides: Quantitative | Critical Reasoning | Reading Comprehension | Ultimate Quant Guide | All You Need for Quant
• Rules: Quantitative | Verbal
If ac/(db) < 0, is d – b < 0 ?
(1) |a − c| = |a| − |c|
This statement holds only if both a and c have the same sign
-------> ac>0
-------> db<0 but not necessarily d - b < 0 [consider this case: d=5 and b=-1: db<0 but d-b >0]
Statement 1 is not sufficient (eliminate A and D)
(2) d – b > d + b
----> d - d > b + b
----> 0 > 2b
----> b < 0
Statement 2 is not sufficient alone (eliminate B)
Both statements together:
----> ac>0
----> db<0 ----> b<0 ----> d>0
the difference between any two different numbers (+ve and -ve) > 0
"C"
(1) |a − c| = |a| − |c|
This statement holds only if both a and c have the same sign
-------> ac>0
-------> db<0 but not necessarily d - b < 0 [consider this case: d=5 and b=-1: db<0 but d-b >0]
Statement 1 is not sufficient (eliminate A and D)
(2) d – b > d + b
----> d - d > b + b
----> 0 > 2b
----> b < 0
Statement 2 is not sufficient alone (eliminate B)
Both statements together:
----> ac>0
----> db<0 ----> b<0 ----> d>0
the difference between any two different numbers (+ve and -ve) > 0
"C"
Posts: 5
Could you please explain why
|a − c| = |a| − |c|
This statement holds only if both a and c have the same sign
Thanks.
|a − c| = |a| − |c|
This statement holds only if both a and c have the same sign
Thanks.
something123
Hi,
If both a and c are of opposite sign....
|a-c| will result in a higher value than |a|-|c|, as a-c will result in numeric value of a and c getting added up, and then MODULUS value will make it a positive value..
lets check with example..
let a = 5, and c = -10...... a-c = 5-(-10)=15 and |15| = 15....... but |a| = |5| and |c| = |-10|, so |a|-|c| = |5|--10|=5-10 =-5....
But if a and b are of same sign...
a= 5 and c=10...
\(|a-c| = |5-10| = |-5| = 5........\) and\(|a|-|c| = |5|-|10| = -5....\) But \(5\neq{-5}\)..
What does it tell us?
That Not only both a and c should be of same sign BUt also numeric value of a should be mor than that of c...... Numeric value is value without sign..
_________________
target760gmat
Joined: 15 Jun 2016
Last visit: 06 Dec 2016
Posts: 42
Location: India
Concentration: Technology, Strategy
Schools: ISB '18 SPJ PGPM"17 NUS '18
GMAT 1: 730 Q50 V39
If ac/(db) < 0, is d – b < 0 ?
(1) |a − c| = |a| − |c|
(2) d – b > d + b
From the question stem, we can infer that either one or three of the variables (a through d) is negative and all of them are non-zero.
(1) It means that a > c and both are of same sign. |a| - |c| is a positive quantity (modulus on left side of the eqn). so |a|>|c|.
(2) this implies b < 0 .
so either a/c = +/+ or -/- giving ac = always +ve
Each stmt is insufficient. Combining two, we know that d > 0.
(+ve) - (-ve) is always > 0
So answer is C
(1) |a − c| = |a| − |c|
(2) d – b > d + b
From the question stem, we can infer that either one or three of the variables (a through d) is negative and all of them are non-zero.
(1) It means that a > c and both are of same sign. |a| - |c| is a positive quantity (modulus on left side of the eqn). so |a|>|c|.
(2) this implies b < 0 .
so either a/c = +/+ or -/- giving ac = always +ve
Each stmt is insufficient. Combining two, we know that d > 0.
(+ve) - (-ve) is always > 0
So answer is C
Schools: Rotman '21
Posts: 6
target760gmat
Hi, can you kindly explain how you arrived at 'd' as >0?
That is the missing link for me to understand the solution to this problem.
Thanks!
Bunuel chetan2u VeritasKarishma
Could you please help me in explaining where I am going wrong. Because I am getting answer B because of following reasons
given \(\frac{ac}{db} <0\)
This implies all 3 have same sign, only one has a different sign
(1) \(|a − c|\) = \(|a| − |c|\)
This says \(a\) and \(c\) are positive but it does not give any info on \(b\) and \(d\)
(2) \(d – b > d + b\)
This says that \(b<0\) and \(d>0.\)
Now that we see that \(b\) and \(d\) have 2 different signs, it hardly matters what is \(a\) and \(c\). \(a\) & \(c\) can be both positive or negative because \(\frac{ac}{db} <0\)
As \(b\) is -ve and \(d\) is +ve, hence b<d.
What am I missing here? Why do we also need 1st statement to find the solution?
Could you please help me in explaining where I am going wrong. Because I am getting answer B because of following reasons
given \(\frac{ac}{db} <0\)
This implies all 3 have same sign, only one has a different sign
(1) \(|a − c|\) = \(|a| − |c|\)
This says \(a\) and \(c\) are positive but it does not give any info on \(b\) and \(d\)
(2) \(d – b > d + b\)
This says that \(b<0\) and \(d>0.\)
Now that we see that \(b\) and \(d\) have 2 different signs, it hardly matters what is \(a\) and \(c\). \(a\) & \(c\) can be both positive or negative because \(\frac{ac}{db} <0\)
As \(b\) is -ve and \(d\) is +ve, hence b<d.
What am I missing here? Why do we also need 1st statement to find the solution?
rsrighosh
d-b>d+b is equal to 2b<0 or b<0.
Nothing about d as d cancels out. It could be 0, <0 or >0.
_________________
Why cant the answer be just B. The stem clearly says and AC/DB <0.
So there is no chance of any of the variables being = 0.
So there is no chance of any of the variables being = 0.
rithhinj
(2) just tells that b < 0. Hence, we know that ac/(db) < 0 and b < 0. How can you decided whether d – b < 0 from that?
_________________
New to the GMAT Club?
- • Questions: Question Bank | Bunuel's Signature Collection
• Tests: GMAT Club Tests | Forum Quiz
• Guides: Quantitative | Critical Reasoning | Reading Comprehension | Ultimate Quant Guide | All You Need for Quant
• Rules: Quantitative | Verbal
Moderator:
Announcements
How to Tell If Your GMAT Prep Resources Are Actually Helping You
Subscribe to GMAT Club for New Podcast Episodes, Debriefs, & Insightful Sessions on GMAT Preparation
Subscribe to GMAT Club for New Podcast Episodes, Debriefs, & Insightful Sessions on GMAT Preparation
Tuck at Dartmouth
AI at Dartmouth Tuck: How the School Is Preparing Leaders for the Age of Artificial Intelligence
Inside the courses, research, and hands-on learning defining wise, decisive leadership in an AI-driven world.
Read More
Inside the courses, research, and hands-on learning defining wise, decisive leadership in an AI-driven world.
Read More
Top 5 GMAT Debrief Videos
Success stories and strategies from high-scoring candidates.