xyz

This topic has expert replies
Master | Next Rank: 500 Posts
Posts: 110
Joined: Sun Jul 18, 2010 4:00 pm
Thanked: 1 times
Followed by:2 members

xyz

by greenwich » Thu Jan 16, 2014 4:52 pm
Is |x-z|=|z-y|?

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

User avatar
Master | Next Rank: 500 Posts
Posts: 490
Joined: Thu Jul 04, 2013 7:30 am
Location: Chennai, India
Thanked: 83 times
Followed by:5 members

by Uva@90 » Thu Jan 16, 2014 7:44 pm
greenwich wrote:Is |x-z|=|z-y|?

(1) x=y
(2)|x|-z=|y|-z
Hi Greenwich,

Question states that,
is distance between x and z is same as z and y ?

so we need to know whether distance of x and y are equal.

statement 1:
x=y
since x =y distance of x => distance of x is same as distance of y
hence sufficient.

statement 2: |x|-z=|y|-z
which can be re-written as |x| = |y|
x=y or x = -y
example: x = -4 and y =4 and z = 1
distance between x and z is 5 and distance between z and y 3
hence distance between x and z may not be same as z and y
hence insufficient.

Answer is A

Note: Modified the solution.

Regards,
Uva.
Last edited by Uva@90 on Thu Jan 16, 2014 9:15 pm, edited 1 time in total.
Known is a drop Unknown is an Ocean

User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pm
Location: New York, NY
Thanked: 13060 times
Followed by:1906 members
GMAT Score:790

by GMATGuruNY » Thu Jan 16, 2014 8:33 pm
greenwich wrote:Is |x-z|=|z-y|?

(1) x=y
(2)|x|-z=|y|-z
|a-b| = |b-a| = the DISTANCE between a and b.

Question rephrased: Is the distance between z and x equal to the distance between z and y?
Put more succinctly:
Is z equidistant from x and y?

Statement 1: x=y
Since x and y are the same value, z must be equidistant from x and y.
SUFFICIENT.

Statement 2: |x|-z = |y|-z
Adding z to each side, we get:
|x| = |y|.

If x=-1, z=0, and y=1, then z is equidistant from x and y:
.....x=-1.....z=0.....y=1.....

If x=-1, y=1, and z=2, then z is closer to y than to x and thus is NOT equidistant from x and y:
.....x=-1................y=1.....z=2.....
INSUFFICIENT.

The correct answer is A.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3