It is currently 17 Oct 2017, 10:06

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 less than 20?

Author Message
TAGS:

Hide Tags

Director
Status: Finally Done. Admitted in Kellogg for 2015 intake
Joined: 25 Jun 2011
Posts: 535

Kudos [?]: 4113 [4], given: 217

Location: United Kingdom
GMAT 1: 730 Q49 V45
GPA: 2.9
WE: Information Technology (Consulting)
Is x less than 20? [#permalink]

Show Tags

20 Mar 2012, 09:07
4
KUDOS
18
This post was
BOOKMARKED
00:00

Difficulty:

5% (low)

Question Stats:

80% (00:21) correct 20% (06:04) wrong based on 780 sessions

HideShow timer Statistics

Is x less than 20?

(1) The sum of x and y is less than 20.
(2) y is less than 20.
[Reveal] Spoiler: OA

_________________

Best Regards,
E.

MGMAT 1 --> 530
MGMAT 2--> 640
MGMAT 3 ---> 610
GMAT ==> 730

Kudos [?]: 4113 [4], given: 217

Math Expert
Joined: 02 Sep 2009
Posts: 41873

Kudos [?]: 128562 [3], given: 12180

Re: Is x less than 20? [#permalink]

Show Tags

20 Mar 2012, 09:17
3
KUDOS
Expert's post
5
This post was
BOOKMARKED
enigma123 wrote:
Is x < 20?

1. Sum of x and y is less than 20

2. y is less than 20

How come the answer is E and not A?

Consider two cases:
x=30 and y=-15;
x=15 and y=-15;

Both examples satisfy the statements and give different answers to the question whether x<20. Not sufficient.

_________________

Kudos [?]: 128562 [3], given: 12180

Manager
Joined: 23 Jun 2008
Posts: 85

Kudos [?]: 45 [0], given: 24

Location: Australia
Schools: AGSM '22
GMAT Date: 04-01-2014
Is x less than 20? [#permalink]

Show Tags

04 Feb 2014, 21:56
nfa1rhp wrote:
Is x less than 20?

1) The sum of x and y is less than 20

2) y is less than 20

I thought working together they would be sufficient but they are not.
[/quote]

Ans E

1 & 2 not sufficient : as difference of two numbers does not implicate their magnitude in any way
_________________

Kudos (+1) if you find this post helpful.

Kudos [?]: 45 [0], given: 24

Intern
Joined: 21 Mar 2013
Posts: 14

Kudos [?]: 3 [0], given: 13

Re: Is x less than 20? [#permalink]

Show Tags

01 Mar 2014, 14:16
but if we solve it like this:
subtract
x+y < 20
y < 20

x+y-y<0
x<0

then x will be certainly less than 20...

Why is this approach flawed ?

Bunuel wrote:
enigma123 wrote:
Is x < 20?

1. Sum of x and y is less than 20

2. y is less than 20

How come the answer is E and not A?

Consider two cases:
x=30 and y=-15;
x=15 and y=-15;

Both examples satisfy the statements and give different answers to the question whether x<20. Not sufficient.

Kudos [?]: 3 [0], given: 13

Math Expert
Joined: 02 Sep 2009
Posts: 41873

Kudos [?]: 128562 [0], given: 12180

Re: Is x less than 20? [#permalink]

Show Tags

02 Mar 2014, 04:20
Expert's post
5
This post was
BOOKMARKED
mariofelix wrote:
but if we solve it like this:
subtract
x+y < 20
y < 20

x+y-y<0
x<0

then x will be certainly less than 20...

Why is this approach flawed ?

Bunuel wrote:
enigma123 wrote:
Is x < 20?

1. Sum of x and y is less than 20

2. y is less than 20

How come the answer is E and not A?

Consider two cases:
x=30 and y=-15;
x=15 and y=-15;

Both examples satisfy the statements and give different answers to the question whether x<20. Not sufficient.

That's wrong because you cannot subtract inequalities with signs in the same direction.

You can only add inequalities when their signs are in the same direction:

If $$a>b$$ and $$c>d$$ (signs in same direction: $$>$$ and $$>$$) --> $$a+c>b+d$$.
Example: $$3<4$$ and $$2<5$$ --> $$3+2<4+5$$.

You can only apply subtraction when their signs are in the opposite directions:

If $$a>b$$ and $$c<d$$ (signs in opposite direction: $$>$$ and $$<$$) --> $$a-c>b-d$$ (take the sign of the inequality you subtract from).
Example: $$3<4$$ and $$5>1$$ --> $$3-5<4-1$$.

Hope it helps.
_________________

Kudos [?]: 128562 [0], given: 12180

Intern
Joined: 15 May 2014
Posts: 1

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

Show Tags

21 Jul 2014, 16:55
Hi All,

I have a question regarding a data sufficiency problem.

Is x less than 20?

1) x + y < 20
2) y is less than 20

My question refers to 1.). In this case, since it says x + y, can we plug in a negative number in for y even with a + sign in front of it?

ex. if x=25, y=-8,
25 + (-8) = 17
we do not know if x<20, therefore INSUFFICIENT

I am sure this question is pretty basic to most, but it is these small details that seem to throw me off while solving DS problems. Any advice would be very helpful.

BTW - This question is from the CAT on GMATPrep software.

Thanks,
Mike

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

Math Expert
Joined: 02 Sep 2009
Posts: 41873

Kudos [?]: 128562 [0], given: 12180

Re: Is x less than 20? [#permalink]

Show Tags

22 Jul 2014, 03:24
MikeA2606 wrote:
Hi All,

I have a question regarding a data sufficiency problem.

Is x less than 20?

1) x + y < 20
2) y is less than 20

My question refers to 1.). In this case, since it says x + y, can we plug in a negative number in for y even with a + sign in front of it?

ex. if x=25, y=-8,
25 + (-8) = 17
we do not know if x<20, therefore INSUFFICIENT

I am sure this question is pretty basic to most, but it is these small details that seem to throw me off while solving DS problems. Any advice would be very helpful.

BTW - This question is from the CAT on GMATPrep software.

Thanks,
Mike

Merging similar topics. Please refer to the discussion above.

As for your question: y is some number, it could be negative, positive or 0. So, you can plug any number you want there.

_________________

Kudos [?]: 128562 [0], given: 12180

Intern
Joined: 17 Oct 2015
Posts: 15

Kudos [?]: [0], given: 20

Schools: LBS '18 (S)
Re: Is x less than 20? [#permalink]

Show Tags

13 Nov 2015, 05:41
For people like me who like equations (especially under time pressure of the GMAT)

For C=>

Just add 1 + 2 (same sign) to get:
x + 2y < 40
x < 40 - 2y

Its then clear x can be any number - depending on y - and less/more than 20... So E.

Further (not needed but why not), the range of x would be:
x > 2y -40
x > 2(20) -40 ( y < 20, so max y ~ 20)
x > 0

Kudos [?]: [0], given: 20

Senior Manager
Joined: 18 Jan 2010
Posts: 257

Kudos [?]: 143 [0], given: 9

Show Tags

27 May 2016, 20:27
rahsin wrote:
Is x less than 20 ?

1. The sum of x and y is less than 20.

2. y is less than 20.

Statement 1

x+y<20

say x=5, y=14, sum is 19. so x+y < 20. Also x is less than 20.

Now take x=25, y=-16, sum is 9. so x+y < 20. BUT x is more than 20.

So not sufficient

Statement 2
This statement does not say anything about x. Clearly Not sufficient.

Combining Statements 1 and 2

Our above examples will suit the purpose, as in both cases y is less than 20.

say x=5, y=14, sum is 19. so x+y < 20. Also y is less than 20. Here x is less than 20
Now take x=25, y=-16, sum is 9. so x+y < 20. Also y < 20. BUT x is more than 20.

So even after combining Not sufficient.

Kudos [?]: 143 [0], given: 9

Manager
Joined: 27 Jan 2013
Posts: 103

Kudos [?]: 68 [0], given: 41

Location: India
GMAT 1: 700 Q49 V35
GPA: 3.7

Show Tags

13 Jul 2016, 14:04
Is x less than 20 ?
(1) The sum of x and y is less than 20.
(2) y is less than 20.

Solution:

Answer should be E. Here it is how:

1: x+y < 20 ---> tells us nothing about y or x. say x=24, y= -10 then x < 20 No. Say x = 17 y =1 then x <20 Yes. --- > Insufficient.
2: y <20 , nothing is told about x. ----> clearly insufficient.

Combined.
x+y < 20 and y <20. Again, use the example given in statement 1. If x=24, y= -10 then x < 20 No. If x = 17, y =1 then x <20 Yes.

Please give kudos if this helps!

Kudos [?]: 68 [0], given: 41

Optimus Prep Instructor
Joined: 06 Nov 2014
Posts: 1905

Kudos [?]: 522 [0], given: 23

Re: Is x less than 20? [#permalink]

Show Tags

16 Jul 2016, 13:02
rraghun wrote:
Is x less than 20 ?
(1) The sum of x and y is less than 20.
(2) y is less than 20.

Required: Is x < 20?
Statement 1: x + y < 20
Case 1: x = 1, y = 18
Case 2: x = 21, y = -29
Nothing can be said about x
INSUFFICIENT

Statement 2: y < 20
This does not give us anything about x
INSUFFICIENT

Combining both statements: x + y < 20 and y < 20
Case 1: x = 21, y = -2
Case 2: x = 18, y = 1
Still nothing can be said about x
INSUFFICIENT

Correct Option: E

Does this help?
_________________

Janielle Williams

Customer Support

Special Offer: $80-100/hr. Online Private Tutoring GMAT On Demand Course$299
Free Online Trial Hour

Kudos [?]: 522 [0], given: 23

Director
Joined: 04 Jun 2016
Posts: 647

Kudos [?]: 365 [0], given: 36

GMAT 1: 750 Q49 V43
Re: Is x less than 20? [#permalink]

Show Tags

17 Jul 2016, 23:50
enigma123 wrote:
Is x less than 20?

(1) The sum of x and y is less than 20.
(2) y is less than 20.

(1) The sum of x and y is less than 20.
x+y<20 ; infinite possible values of x ; NOT SUFFICIENT

(2) y is less than 20
Doesn't even talk about x; NOT SUFFICIENT

MERGING
x+less than 20<20
Case 1 ) Y is negative
x+(-30)<20 ==> x<50 {{{ Is x less than 20? = NO}}}

Case 1 ) Y is Positive
x+14<20 ==> x<6 {{{Is x less than 20? =YES}}}

NOT SUFFICIENT

_________________

Posting an answer without an explanation is "GOD COMPLEX". The world doesn't need any more gods. Please explain you answers properly.
FINAL GOODBYE :- 17th SEPTEMBER 2016. .. 16 March 2017 - I am back but for all purposes please consider me semi-retired.

Kudos [?]: 365 [0], given: 36

Director
Joined: 26 Oct 2016
Posts: 695

Kudos [?]: 179 [0], given: 855

Location: United States
Schools: HBS '19
GMAT 1: 770 Q51 V44
GPA: 4
WE: Education (Education)
Re: Is x less than 20? [#permalink]

Show Tags

26 Jan 2017, 06:06
Statement 1: (x + y) < 20
Possible combinations,
1. x = 50, y = -10
2. x = 10, y = 5
so, value of x can be more than 20 or less than 20 we don't know about that.

Not sufficient

Statement 2: No information regarding x.

Not sufficient

1 & 2 Together: Same examples as in statement 1.

Not sufficient

_________________

Thanks & Regards,
Anaira Mitch

Kudos [?]: 179 [0], given: 855

Re: Is x less than 20?   [#permalink] 26 Jan 2017, 06:06
Display posts from previous: Sort by