|
|
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.
23 Jun 2017, 08:27
Kudos
Bookmarks
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
15%
(low)
Question Stats:
78% (01:34) correct
22%
(01:35)
wrong
based on 102
sessions
History
Date
Time
Result
Not Attempted Yet
What is the value of \(b – 2c\)?
(1) \(ab – 2cd + bd – 2ac = 8\)
(2) \(a = 4 – d\)
(1) \(ab – 2cd + bd – 2ac = 8\)
(2) \(a = 4 – d\)
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
23 Jun 2017, 11:49
Kudos
Bookmarks
Bunuel
The best way to do this sort of problem is usually to try to isolate what we're being asked to solve for.
Statement 1:
\(ab - 2cd + bd - 2ac = 8\)
Let's try get all the "b" terms together and all the "2c" terms together:
\(ab + bd - 2ac - 2cd = 8\)
Now we can factor out the b in the first two terms and a negative 2c in the second two terms (be careful to change the signs properly):
\(b(a + d) -2c (a + d) = 8\)
Finally, we can divide by (a+d):
\(b - 2c = \frac{8}{a+d}\)
At this point, we're stuck. We can't solve for \(b-2c\) without knowing the value of \(a+d\)
Insufficient.
Statement 2:
Statement 2 doesn't give us any information about b or about c.
Insufficient.
Combined:
We can rewrite Statement 2 as:
\(a+d = 4\)
Now we can substitute in our rewritten first equation:
\(b - 2c = \frac{8}{4}\)
\(b - 2c = 2\)
Sufficient.
C.
24 Jun 2017, 06:06
Kudos
Bookmarks
What is the value of b–2cb–2c?
(1) ab–2cd+bd–2ac=8ab–2cd+bd–2ac=8
(2) a=4–d
Solution:
Statement 1: Rearranging,
we get a(b-2c)+ d(b-2c)=8
Taking out the common factor, (b-2c) (a+d)=8.
We can't find the unique value of either of terms as infinite values are possible.
Statement 2: Insufficient on its own.
Combining St1 and St2,
We get a unique value of b-2c. We get 4 as the value.
Therefore, the answer is Option C.
(1) ab–2cd+bd–2ac=8ab–2cd+bd–2ac=8
(2) a=4–d
Solution:
Statement 1: Rearranging,
we get a(b-2c)+ d(b-2c)=8
Taking out the common factor, (b-2c) (a+d)=8.
We can't find the unique value of either of terms as infinite values are possible.
Statement 2: Insufficient on its own.
Combining St1 and St2,
We get a unique value of b-2c. We get 4 as the value.
Therefore, the answer is Option C.
