It is currently 20 Oct 2017, 22:36

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

What is the value of y?

Author Message
TAGS:

Hide Tags

Intern
Joined: 01 Oct 2010
Posts: 16

Kudos [?]: 11 [2], given: 2

What is the value of y? [#permalink]

Show Tags

29 Oct 2010, 08:28
2
KUDOS
6
This post was
BOOKMARKED
00:00

Difficulty:

55% (hard)

Question Stats:

56% (01:20) correct 44% (01:22) wrong based on 197 sessions

HideShow timer Statistics

What is the value of y?

(1) 3|x^2 – 4| = y – 2

(2) |3 – y| = 11

I understand that (1) alone is insufficient, but the explanation says that from (1) we can determine that y is greater than or equal to 2. Can someone please explain how this is deduced? Thanks!
[Reveal] Spoiler: OA

Last edited by Bunuel on 12 Jul 2013, 02:58, edited 1 time in total.
Renamed the topic and edited the question.

Kudos [?]: 11 [2], given: 2

Math Expert
Joined: 02 Sep 2009
Posts: 41892

Kudos [?]: 129055 [2], given: 12187

Re: Data Sufficiency Question: MGMAT Cat 1 Problem #4 [#permalink]

Show Tags

29 Oct 2010, 08:32
2
KUDOS
Expert's post
2
This post was
BOOKMARKED
MLF44 wrote:
I understand that (1) alone is insufficient, but the explanation says that from (1) we can determine that y is greater than or equal to 2. Can someone please explain how this is deduced? Thanks!

*note that in (1) "x2" is meant to be x squared

What is the value of y?
(1) 3|x^2 -4| = y - 2
(2) |3 - y| = 11

(1) As we are asked to find the value of $$y$$, from this statement we can conclude only that $$y\geq{2}$$, as LHS is absolute value which is never negative, hence RHS als can not be negative. Not sufficient.

To elaborate more left hand side is some absolute value, absolute value is always non-negative: $$|some \ expression|\geq{0}$$, so RHS is also non-negative --> $$y-2\geq{0}$$ --> $$y\geq{2}$$

(2) $$|3 - y| = 11$$:

$$y<3$$ --> $$3-y=11$$ --> $$y=-8$$;
$$y\geq{3}$$ --> $$-3+y=11$$ --> $$y=14$$.

Two values for $$y$$. Not sufficient.

(1)+(2) As from (1) $$y\geq{2}$$, then $$y=14$$. Sufficient.

For more on absolute values.
Theory: math-absolute-value-modulus-86462.html
Practice: inequality-and-absolute-value-questions-from-my-collection-86939.html

Hope it helps.
_________________

Kudos [?]: 129055 [2], given: 12187

Intern
Joined: 01 Oct 2010
Posts: 16

Kudos [?]: 11 [0], given: 2

Re: Data Sufficiency Question: MGMAT Cat 1 Problem #4 [#permalink]

Show Tags

29 Oct 2010, 08:37
DUH! Now I see it. Thank you so much!

Kudos [?]: 11 [0], given: 2

Intern
Joined: 14 Sep 2010
Posts: 23

Kudos [?]: 64 [0], given: 0

Show Tags

29 Jan 2011, 03:50
What is the value of y?

(1) 3|x2 – 4| = y – 2

(2) |3 – y| = 11

My question is, that in the Manhattan Gmat guide, they always ask you to find solutions of the absolute value equation, and then PLUG both values in to the original equation. In case if one of those values dont match up, then that solution can be eliminated. If in either of the equations , we would find a value which could not work, then could we safely count that as sufficiency for that statement, or would we have to still assume that both are possible so not sufficient?

Thanks

Kudos [?]: 64 [0], given: 0

Math Expert
Joined: 02 Sep 2009
Posts: 41892

Kudos [?]: 129055 [0], given: 12187

Re: Equation problem Absolute values [#permalink]

Show Tags

29 Jan 2011, 04:00
What is the value of y?

(1) 3|x2 – 4| = y – 2

(2) |3 – y| = 11

My question is, that in the Manhattan Gmat guide, they always ask you to find solutions of the absolute value equation, and then PLUG both values in to the original equation. In case if one of those values dont match up, then that solution can be eliminated. If in either of the equations , we would find a value which could not work, then could we safely count that as sufficiency for that statement, or would we have to still assume that both are possible so not sufficient?

Thanks

Merging similar topics. This question, along with other absolute value/inequality questions, is also discussed here: inequality-and-absolute-value-questions-from-my-collection-86939.html

As for your question: in DS questions, when we are asked to determine value of an unknown, statement is sufficient if it gives single numerical value of this unknown. So if you have two solutions for a variable out of which one is not valid for some reason then you are left with only one solution and thus the statement is sufficient (of course if you are asked to find the value of this variable).
_________________

Kudos [?]: 129055 [0], given: 12187

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16637

Kudos [?]: 273 [1], given: 0

Re: What is the value of y? [#permalink]

Show Tags

27 Nov 2014, 08:23
1
KUDOS
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 [?]: 273 [1], given: 0

GMAT Club Legend
Joined: 09 Sep 2013
Posts: 16637

Kudos [?]: 273 [1], given: 0

Re: What is the value of y? [#permalink]

Show Tags

10 Dec 2015, 09:57
1
KUDOS
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 [?]: 273 [1], given: 0

Manager
Joined: 01 Dec 2016
Posts: 117

Kudos [?]: 13 [0], given: 32

Location: Cote d'Ivoire
Concentration: Finance, Entrepreneurship
WE: Investment Banking (Investment Banking)
Re: What is the value of y? [#permalink]

Show Tags

30 May 2017, 13:34
easy when you start by stat (2)
(2) give you y=14 or y=-8. two possible value of y. Statm2 alone is insuff
(1) we don't know the value of x, hence statm1 alone is insuff. but statm1 tells us that y must be greater than 2

Both statm lead to y=14, Hence sufficient

_________________

What was previously thought to be impossible is now obvious reality.
In the past, people used to open doors with their hands. Today, doors open "by magic" when people approach them

Kudos [?]: 13 [0], given: 32

Re: What is the value of y?   [#permalink] 30 May 2017, 13:34
Display posts from previous: Sort by