Data sufficiency help

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Data sufficiency help

by snehavenkat » Mon Oct 21, 2013 10:56 pm
gmat official guide 13th edition
56th problem.
What is the Value of z in the triangle above?
1. x+y=139 ---> Sufficient x+y+z= 180 substitute x+y
2. y+z=108 ---> x+y+z=180 substitute y+z and u get the value of x then u can rewrite as z=108-y n again substitute it and can get the value of z.
According to the guide the correct answer is A.
please explain why not D..

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by theCodeToGMAT » Mon Oct 21, 2013 11:22 pm
To find: "z"

x + y + z = 180*

Statement 1:
x + y = 139
Z = 180 - 139 = 41
SUFFICIENT

Statement 2:
y+z = 108
x = 180-108 = 72
You cannot comment on value of "z"
INSUFFICIENT


Answer [spoiler]{A}[/spoiler]
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by theCodeToGMAT » Mon Oct 21, 2013 11:25 pm
snehavenkat wrote: 2. y+z=108 ---> x+y+z=180 substitute y+z and u get the value of x then u can rewrite as z=108-y n again substitute it and can get the value of z.
we found out value for "x" & not "y" .. so we cannot do anything by z=108-y
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by [email protected] » Tue Oct 22, 2013 12:07 am
Hi snehavenkat,

In DS questions, when you're asked to find the "value" of something, the question is "really" asking if the value is consistent or inconsistent.

In this DS question, Fact 1 tells you x + y = 139, so if you "plug" that into x + y + z = 180, then you CAN figure out z (it equals 41) and that's the only possible answer. Thus, Fact 1 is SUFFICIENT.

In Fact 2, we're told that y + z = 108
So....there are possibilities....
y = 54, z = 54
y = 53, z = 55
etc.

Thus, z can be different values and there's no way to sure which one it actually is. Thus, Fact 2 is INSUFFICIENT.

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by sanju09 » Tue Oct 22, 2013 3:20 am
snehavenkat wrote:gmat official guide 13th edition
56th problem.
What is the Value of z in the triangle above?
1. x+y=139 ---> Sufficient x+y+z= 180 substitute x+y
2. y+z=108 ---> x+y+z=180 substitute y+z and u get the value of x then u can rewrite as z=108-y n again substitute it and can get the value of z.
According to the guide the correct answer is A.
please explain why not D..
We cannot find z from y + z = 108, hence (2) is not sufficient.
The mind is everything. What you think you become. -Lord Buddha



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Re:

by Newaz111 » Mon Feb 07, 2022 11:51 pm
[email protected] wrote:
Tue Oct 22, 2013 12:07 am
Hi snehavenkat,

In DS questions, when you're asked to find the "value" of something, the question is "really" asking if the value is consistent or inconsistent.

In this DS question, Fact 1 tells you x + y = 139, so if you "plug" that into x + y + z = 180, then you CAN figure out z (it equals 41) and that's the only possible answer. Thus, Fact 1 is SUFFICIENT.

In Fact 2, we're told that y + z = 108
So....there are possibilities....
y = 54, z = 54
y = 53, z = 55
etc.

Thus, z can be different values and there's no way to sure which one it actually is. Thus, Fact 2 is INSUFFICIENT.

GMAT assassins aren't born, they're made,
Rich
Thank you so much Rich. Now I found the logic.