What is the value of x?

Question

https://gmatclub.com/forum/download/file.php?id=24536 What is the value of x? (1) l1 is parallel to l2 (2) y = 70 untitled.GIF

BrentGMATPrepNow · Accepted Answer

Target question :    What is the value of x?

IMPORTANT : For geometry Data Sufficiency questions, we are typically checking to see whether the statements "lock" a particular angle, length, or shape into having just one possible measurement. This concept is discussed in much greater detail in the video below.

Notice that  neither statement affects the placement of line3

So, let's jump straight to....
   Statements 1 and 2 combined    
Consider the following two diagrams that both satisfy the conditions in statements 1 AND 2. 
 https://i.imgur.com/iNuCc5R.png

https://i.imgur.com/G3NSn5Q.png

Notice that, each time we move line3, the value of x changes. 
So,  there's no way to determine (i.e., lock in) the value of x 
Since we cannot answer the  target question  with certainty, the combined statements are NOT SUFFICIENT

Answer: E
 
RELATED VIDEOS
 https://www.youtube.com/watch?v=wetqSGMdY7Y

https://www.youtube.com/watch?v=F26uam3kmCU

Gnpth · Answer

Statement 1: It just says about the lines  l1  and  l2 . Nothing about the other 2 lines L3 and L4. So insufficient.

Statement 2: Says only about the angle of y. Nothing about the lines. So insufficient.

Combining (1) & (2): Still no information on lines L3 and L4.

So the answer is E.

Nunuboy1994 · Answer

Statement 1

l1 parallel to l2 - clearly insufficient because no values given or implied

Statement 2

y=70 we cannot apply transversal properties unless we know that both l1 and l2 and l3 and l4 are all parallel

insuff

Statement 1 and Statement 2

Insuff- we can only find the answer if both vertical lines are also parallel

TestPrepUnlimited · Answer

Analyzing the question: 
The angles x and y here are too far apart, we need the lines  L1 L2  to be parallel AND the lines  L3 L4  to be parallel in order to have the relation  x + y = 180 . That is already two pieces of information needed just to claim the relation between x and y, besides that we still need to know y (given they don't give away x). The statements give only one piece of information each, so combined this is still insufficient.

Ans: E

aritranandy8 · Answer

VeritasKarishma  plz explain

CEdward · Answer

The question is asking what the angle of x is. (Missing from the question btw). Anyway.

To determine what x is, we need to know whether the two pairs of seemingly 'parallel' lines are in fact, parallel. Else, the value of x can change even when the statements are satisfied.

(1) l1 is parallel to l2
This is insufficient b/c we don't know what y is.

(2) y = 70
This is insufficient b/c we don't know whether l1 and l2 are parallel, and whether l3 and l4 are parallel.

Combined: We still don't know whether l3 and l4 are parallel. You need both sets of lines to be parallel to conclude that x = 70

prithviraj99 · Answer

Image tricked me to assume that l3 and l4 are parallel. Classic C-trap question

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What is the value of x?

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GMAT Data Sufficiency (DS) Questions

What is the value of x?

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