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29 Aug 2018, 01:37
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B
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Difficulty:
5%
(low)
Question Stats:
91% (00:43) correct
9%
(01:13)
wrong
based on 139
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What is the value of x in the figure above?
(1) x > 40
(2) x = y
Attachment:
image001.gif [ 714 Bytes | Viewed 4025 times ]
29 Aug 2018, 03:18
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Bunuel
Question stem:- What is the value of x?
St1:- x > 40
We can say that x+y+40=180 (Angles on a straight line add up to 180)
Or, x+y=140
y is unknown, so x can't be determined.
St2:- x = y
We have, x+y+40=180
Or, x+x=140
Or, 2x=140
Or, x=70.
Sufficient.
Ans. (B)
29 Aug 2018, 07:09
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Bunuel
IMPORTANT ASIDE: On GMAT diagrams, all lines that APPEAR straight ARE straight
I mention this in case some students feel that angles x°, y° and 40° may not be on the straight line.
So, given all of this, we can say: x° + y° + 40° = 180° (since the 3 angles are on the same line)
For more on what can and cannot be assumed on GMAT Geometry questions, see the video below.
Target question: What is the value of x?
Statement 1: x > 40
Let's TEST some values, keeping in mind that it must also be true that x° + y° + 40° = 180°
There are several values of x and y that satisfy statement 1. Here are two:
Case a: x = 50, y = 90 (this also satisfies the condition that x° + y° + 40° = 180°) In this case, the answer to the target question is x = 50
Case b: x = 60, y = 80 (this also satisfies the condition that x° + y° + 40° = 180°) In this case, the answer to the target question is x = 60
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT
Statement 2: x = y
Take our "given" equation x° + y° + 40° = 180° and...
..replace y with x to get: x° + x° + 40° = 180°
Simplify left side: 2x° + 40° = 180°
Subtract 40° from both sides to get: 2x° = 140°
Solve: x = 70
So, the answer to the target question is x = 70
Since we can answer the target question with certainty, statement 2 is SUFFICIENT
Answer: B
Cheers,
Brent
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