GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

It is currently 06 Aug 2020, 02:48

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

What is the value of xy - yz? (1) y = 2 (2) x - z = 5

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 65829
What is the value of xy - yz? (1) y = 2 (2) x - z = 5  [#permalink]

Show Tags

New post 23 Sep 2018, 20:21
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

90% (00:27) correct 10% (00:50) wrong based on 135 sessions

HideShow timer Statistics

Manager
Manager
User avatar
S
Joined: 17 Mar 2018
Posts: 69
Reviews Badge
What is the value of xy - yz? (1) y = 2 (2) x - z = 5  [#permalink]

Show Tags

New post 23 Sep 2018, 20:41
What is the value of xy - yz?

y(x-z)?

(1) y = 2
=> 2(x-z) Not Sufficient.

(2) x - z = 5
=> y(5) Not Sufficient.

(1)+(2)
xy-yz= y(x-z)= 2(5)= 10 Sufficient

Ans= C
GMAT Club Legend
GMAT Club Legend
User avatar
V
Joined: 11 Sep 2015
Posts: 4999
Location: Canada
GMAT 1: 770 Q49 V46
What is the value of xy - yz? (1) y = 2 (2) x - z = 5  [#permalink]

Show Tags

New post 05 Mar 2020, 06:24
Top Contributor
1
Bunuel wrote:
What is the value of xy - yz?


(1) y = 2
(2) x - z = 5


Important: Notice that we can take xy - yz and factor out the y to get the following equivalent expression: y(x - z)

Target question: What is the value of y(x - z)?

Statement 1: y = 2
Our goal is to determine the value of y(x - z)
We now know the value of y, but we don't know the value of (x - z)
Statement 1 is NOT SUFFICIENT

Statement 2: x - z = 5
Our goal is to determine the value of y(x - z)
We now know the value of (x - z), but we don't know the value of y
Statement 2 is NOT SUFFICIENT

Statements 1 and 2 combined
Statement 1 tells us that y = 2
Statement 2 tells us that x - z = 5
So, y(x - z) = 2(5) = 10
Since we can answer the target question with certainty, the combined statements are SUFFICIENT

Answer: C

Cheers,
Brent
_________________
If you enjoy my solutions, you'll love my GMAT prep course.

Image
Intern
Intern
avatar
B
Joined: 24 Apr 2020
Posts: 45
Re: What is the value of xy - yz? (1) y = 2 (2) x - z = 5  [#permalink]

Show Tags

New post 30 Apr 2020, 08:00
The question has three variables.
A has the value of only y..since we don't have the values of x and z, we cannot find the value of y(x-z). So Insufficient
B gives the value of x-z but not y. So Insufficient.
But together, we can find y(x-z) using both A and B. So C

Posted from my mobile device
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 9277
GMAT 1: 760 Q51 V42
GPA: 3.82
Re: What is the value of xy - yz? (1) y = 2 (2) x - z = 5  [#permalink]

Show Tags

New post 30 Apr 2020, 20:54
Bunuel wrote:
What is the value of xy - yz?


(1) y = 2

(2) x - z = 5


Forget conventional ways of solving math questions. For DS problems, the VA (Variable Approach) method is the quickest and easiest way to find the answer without actually solving the problem. Remember that equal numbers of variables and independent equations ensure a solution.
Visit https://www.mathrevolution.com/gmat/lesson for details.

The first step of the VA (Variable Approach) method is to modify the original condition and the question. We then recheck the question. We should simplify conditions if necessary.
The question \(xy - yz\) is equivalent to \(y(x-z)\) by factoring.

Since we have 3 variables (\(x, y\) and \(z\)) and 0 equations, E is most likely the answer. So, we should consider conditions 1) & 2) together first. After comparing the number of variables and the number of equations, we can save time by considering conditions 1) & 2) together first.

Conditions 1) & 2)

\(xy - yz = y(x-z) = 2 \cdot 5 = 10\) since we have \(y = 2\) and \(x - z = 5\).

Since both conditions together yield a unique solution, they are sufficient.

Therefore, C is the answer.

In cases where 3 or more additional equations are required, such as for original conditions with “3 variables”, or “4 variables and 1 equation”, or “5 variables and 2 equations”, conditions 1) and 2) usually supply only one additional equation. Therefore, there is an 80% chance that E is the answer, a 15% chance that C is the answer, and a 5% chance that the answer is A, B or D. Since E (i.e. conditions 1) & 2) are NOT sufficient, when taken together) is most likely to be the answer, it is generally most efficient to begin by checking the sufficiency of conditions 1) and 2), when taken together. Obviously, there may be occasions on which the answer is A, B, C or D.
_________________
MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $79 for 1 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"
GMAT Club Bot
Re: What is the value of xy - yz? (1) y = 2 (2) x - z = 5   [#permalink] 30 Apr 2020, 20:54

What is the value of xy - yz? (1) y = 2 (2) x - z = 5

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  





Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne