It is currently 14 Dec 2017, 20:44

### GMAT Club Daily Prep

#### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Is x = |y - z|?

Author Message
TAGS:

### Hide Tags

Director
Joined: 07 Jun 2004
Posts: 609

Kudos [?]: 969 [0], given: 22

Location: PA
Is x = |y - z|? [#permalink]

### Show Tags

21 Sep 2010, 06:23
5
This post was
BOOKMARKED
00:00

Difficulty:

45% (medium)

Question Stats:

54% (00:49) correct 46% (00:55) wrong based on 279 sessions

### HideShow timer Statistics

Is x = |y - z|?

(1) x = y - z
(2) y > z
[Reveal] Spoiler: OA

_________________

If the Q jogged your mind do Kudos me : )

Kudos [?]: 969 [0], given: 22

Math Expert
Joined: 02 Sep 2009
Posts: 42604

Kudos [?]: 135674 [0], given: 12706

Is x = |y - z|? [#permalink]

### Show Tags

21 Sep 2010, 06:36
Expert's post
1
This post was
BOOKMARKED
rxs0005 wrote:
is x = | y - z | ?

x = y - z

y > z

Is $$x=|y-z|$$?

If $$y-z\geq{0}$$ then the question becomes is $$x=y-z$$?
If $$y-z\leq{0}$$ then the question becomes is $$x=-(y-z)$$?

Basically the question asks whether the distance between $$y$$ and $$z$$ on the number line equals to $$x$$. Note that $$x$$ as it's equal to the distance (or to the absolute value) cannot be negative.

(1) $$x=y-z$$, not sufficient, because we don't know whether $$y-z>\geq{0}$$.
(2) $$y-z>0$$ --> $$|y-z|=y-z$$, but still not sufficient as no info about $$x$$.

(1)+(2) From (1) $$x=y-z$$ and from (2) $$|y-z|=y-z$$ --> $$x=|y-z|=y-z$$. Sufficient.

Similar questions:
ds-question-97761.html?hilit=similar%20question#p753020
abs-equation-from-gmatprep-84821.html
_________________

Kudos [?]: 135674 [0], given: 12706

Manager
Joined: 06 Aug 2010
Posts: 217

Kudos [?]: 233 [0], given: 5

Location: Boston

### Show Tags

21 Sep 2010, 09:39
rxs0005 wrote:
is x = | y - z | ?

x = y - z

y > z

Since absolute value can't be negative, for x to be equal to |y - z|, x must be greater than or equal to 0.

(1) If y > z, then x is positive and x = |y - z| = y - z. However, if y < z, then x is negative and cannot be equal to the absolute value. Insufficient.

(2) This tells you nothing about x. Insufficient.

Together: Since y > z, we know that y - z > 0. Therefore |y - z| = y - z, and we know that x = y - z. Sufficient. (C).

Kudos [?]: 233 [0], given: 5

Math Expert
Joined: 02 Sep 2009
Posts: 42604

Kudos [?]: 135674 [0], given: 12706

Is x = |y - z|? [#permalink]

### Show Tags

05 Jul 2013, 09:27

Kudos [?]: 135674 [0], given: 12706

Senior Manager
Joined: 13 May 2013
Posts: 458

Kudos [?]: 204 [0], given: 134

Re: Is x = |y - z|? [#permalink]

### Show Tags

05 Jul 2013, 09:35
Hi,

So what you are saying is that the stem asks whether positive x (because its set to an absolute value) is = to y-z or z-y but #1 could allow for x to be a negative value? Thus making it insufficient?

Kudos [?]: 204 [0], given: 134

Math Expert
Joined: 02 Sep 2009
Posts: 42604

Kudos [?]: 135674 [0], given: 12706

Re: Is x = |y - z|? [#permalink]

### Show Tags

06 Jul 2013, 00:47
WholeLottaLove wrote:
Hi,

So what you are saying is that the stem asks whether positive x (because its set to an absolute value) is = to y-z or z-y but #1 could allow for x to be a negative value? Thus making it insufficient?

Yes. For (1) x could be negative (when y - z is negative). Now if x is negative it cannot equal to absolute value.

Hope it's clear.
_________________

Kudos [?]: 135674 [0], given: 12706

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 4476

Kudos [?]: 3155 [0], given: 0

GPA: 3.82
Re: Is x = |y - z|? [#permalink]

### Show Tags

21 Nov 2015, 09:22
Forget conventional ways of solving math questions. In DS, Variable approach is the easiest and quickest way to find the answer without actually solving the problem. Remember equal number of variables and independent equations ensures a solution.

Is x = |y - z|?

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

|a|=a when a>=0,

There are 3 variables (x,y,z) but only 2 equations are given by the 2 conditions, so there is high chance (E) will be our answer.
If we combine the 2 equations,
from y-z>0, x=|y-z|? --> x=y-z?
this is always 'yes' so this is sufficient and the answer becomes (C).

For cases where we need 3 more equations, such as original conditions with “3 variables”, or “4 variables and 1 equation”, or “5 variables and 2 equations”, we have 1 equation each in both 1) and 2). Therefore, there is 80% chance that E is the answer (especially about 90% of 2 by 2 questions where there are more than 3 variables), while C has 15% chance. These two are the majority. In case of common mistake type 3,4, the answer may be from A, B or D but there is only 5% chance. Since E is most likely to be the answer using 1) and 2) separately according to DS definition (It saves us time). Obviously there may be cases where the answer is A, B, C or D.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself

Kudos [?]: 3155 [0], given: 0

Board of Directors
Joined: 17 Jul 2014
Posts: 2698

Kudos [?]: 450 [0], given: 208

Location: United States (IL)
Concentration: Finance, Economics
GMAT 1: 650 Q49 V30
GPA: 3.92
WE: General Management (Transportation)
Re: Is x = |y - z|? [#permalink]

### Show Tags

28 Jan 2016, 19:32
y-z can be negative, in this case, x is not equal to |y-z|. 1 insufficient.
2 alone - insufficient, as nothing is specified about z.

1+2 -> we know that y-z is positive, and this is the same as |y-z|, thus both are sufficient.

C

Kudos [?]: 450 [0], given: 208

Intern
Joined: 23 Oct 2014
Posts: 12

Kudos [?]: [0], given: 18

Re: Is x = |y - z|? [#permalink]

### Show Tags

23 May 2016, 23:25
Hello Experts,
I interpreted the question as "Is X = positive " since the abs value is always positive.
Considering the above understanding I concluded that Option 1 is insufficient since we don't know the signs of z or y but I chose Option 2 (B) because it's given y>z. I substituted all combinations of positive and negative values for y and z and found that we can answer the question if X is positive. (eg: y=-1,z=-2 or y=2,z=-5 or y=3,z=2 --- for all of these I got X as positive)
Kindly help me understand where is my reasoning incorrect.

Thanks & Regards,
Nab

Kudos [?]: [0], given: 18

Math Expert
Joined: 02 Sep 2009
Posts: 42604

Kudos [?]: 135674 [1], given: 12706

Re: Is x = |y - z|? [#permalink]

### Show Tags

24 May 2016, 02:54
1
KUDOS
Expert's post
Nab77 wrote:
Hello Experts,
I interpreted the question as "Is X = positive " since the abs value is always positive.
Considering the above understanding I concluded that Option 1 is insufficient since we don't know the signs of z or y but I chose Option 2 (B) because it's given y>z. I substituted all combinations of positive and negative values for y and z and found that we can answer the question if X is positive. (eg: y=-1,z=-2 or y=2,z=-5 or y=3,z=2 --- for all of these I got X as positive)
Kindly help me understand where is my reasoning incorrect.

Thanks & Regards,
Nab

The question cannot be translated as "is x positive". The question asks whether the distance between y and z on the number line equals to x. Check complete solutions above.
_________________

Kudos [?]: 135674 [1], given: 12706

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 4476

Kudos [?]: 3155 [0], given: 0

GPA: 3.82
Re: Is x = |y - z|? [#permalink]

### Show Tags

25 May 2016, 02:59
There are 3 variables in the original condition (x, y, and z). In order to match the number of variables to the number of equations, we need 3 equations. Since the condition 1) and the condition 2) each has 1 equation, we lack 1 equation. There is high chance that E is the correct answer. Using both the condition 1) and the condition 2), from y-z>0, we get |y-z|=y-z. Then, the question becomes x=|y-z|?, x=y-z?. The answer is always yes and the conditions are sufficient. Therefore, the correct answer is C.
Attachments

variable approach's answer probability.jpg [ 219.74 KiB | Viewed 983 times ]

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
Find a 10% off coupon code for GMAT Club members.
“Receive 5 Math Questions & Solutions Daily”
Unlimited Access to over 120 free video lessons - try it yourself

Kudos [?]: 3155 [0], given: 0

Senior Manager
Joined: 07 Sep 2014
Posts: 482

Kudos [?]: 40 [0], given: 342

Concentration: Finance, Marketing
Re: Is x = |y - z|? [#permalink]

### Show Tags

30 Aug 2016, 01:27
Is x = |y - z|?

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

X has to be positive. for Is x = |y - z|?

1> we don't know if y>z or not. not sufficient.

2> we know relation between y and z but no info about X.
combined. yes

Kudos [?]: 40 [0], given: 342

Non-Human User
Joined: 09 Sep 2013
Posts: 14833

Kudos [?]: 287 [0], given: 0

Re: Is x = |y - z|? [#permalink]

### Show Tags

21 Nov 2017, 07:14
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

Kudos [?]: 287 [0], given: 0

Re: Is x = |y - z|?   [#permalink] 21 Nov 2017, 07:14
Display posts from previous: Sort by