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Nchoward
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Princeton Review Drill - I don't understand Updated on: 30 Aug 2011, 07:20
Originally posted by Nchoward on 30 Aug 2011, 05:06.
Last edited by Nchoward on 30 Aug 2011, 07:20, edited 1 time in total.
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E
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

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25% (00:06) correct 75% (00:48) wrong based on 4 sessions

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In the PR Cracking the GMAT 2012 (Drill 7 #8 pg 196) there is a triangle not drawn to scale. It "appears" to be a an isosceles triangle with the the diagram drawn: Lower left angle is ~60 degrees with leg value A. Angle labeled X. The "top point" of the triangle at the top is labeled B with and drawn ~30degrees. No angle label. The final angle (lower right) is drawn ~60 degrees (labeled Y) and the leg is labeled C. The data sufficiency question is:

What is the value of x in ABC shown above?
1) Angle y = 80 degrees
2) AB = BC

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I quickly determined it could only be C or E but chose the answer C because, if we know AB=AC and they are shown opposite the angles X and Y, can't we determine that X also equals 80 degrees? The PR says the answer is E beause "we don't actually know the two sides of the triangle are equal."

I'm confused - what does AB=BC mean if it doesn't mean they are equal? I appreciate any help you can give me. NC



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E
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Berbatov
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Princeton Review Drill - I don't understand 30 Aug 2011, 07:13
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Why not c?

If we know that AC=AB, then y and z (the angle at b) are equal and both 80°, hence 160 in total. Therefore, x is 20
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Nchoward
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Princeton Review Drill - I don't understand 30 Aug 2011, 07:22
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Berbatov
Why not c?

If we know that AC=AB, then y and z (the angle at b) are equal and both 80°, hence 160 in total. Therefore, x is 20
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THANKS - but I totally copied the problem incorrectly! The sides that = each other are AB and BC.

Sorry for the confusion. NC
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Berbatov
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Princeton Review Drill - I don't understand 30 Aug 2011, 07:24
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Nchoward
Berbatov
Why not c?

If we know that AC=AB, then y and z (the angle at b) are equal and both 80°, hence 160 in total. Therefore, x is 20

THANKS - but I totally copied the problem incorrectly! The sides that = each other are AB and BC.

Sorry for the confusion. NC
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Should still be c though^^

If both legs are equal, y and x also have to be equal...
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MrClean
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Princeton Review Drill - I don't understand 10 Nov 2011, 21:20
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It definitely looks like it should be C. I am in the same boat. Just starting my review and I'd hate to get something seemingly basic like this incorrect...is this confirmed?
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nikhilsamuel89
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Princeton Review Drill - I don't understand 22 Nov 2011, 07:38
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No values given.
we need to find x.
1.y=80 deg. We cannot find x from this since we don't know the other angle. NOT SUFFICIENT
2.given: AB=BC. implies x = y. But y = unknown. NOT SUFFICIENT
If both are taken together, y=80 AND x=y, hence x=80. Hence, C.
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Princeton Review Drill - I don't understand 23 Nov 2011, 07:40
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Unless you made some error copying the question, the OA is incorrect. It should be C. If AB=BC, implies, it is an isosceles triangle. Hence, X=Y, and Y is given as 80. Thus X=80.

I don't see how E can be the answer.



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