GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 14 Nov 2018, 22:34

Close

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
Your Progress

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

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel
Events & Promotions in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • $450 Tuition Credit & Official CAT Packs FREE

     November 15, 2018

     November 15, 2018

     10:00 PM MST

     11:00 PM MST

    EMPOWERgmat is giving away the complete Official GMAT Exam Pack collection worth $100 with the 3 Month Pack ($299)
  • Free GMAT Strategy Webinar

     November 17, 2018

     November 17, 2018

     07:00 AM PST

     09:00 AM PST

    Nov. 17, 7 AM PST. Aiming to score 760+? Attend this FREE session to learn how to Define your GMAT Strategy, Create your Study Plan and Master the Core Skills to excel on the GMAT.

M07-31

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50585
M07-31  [#permalink]

Show Tags

New post 15 Sep 2014, 23:35
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

73% (00:40) correct 27% (00:32) wrong based on 59 sessions

HideShow timer Statistics

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50585
Re M07-31  [#permalink]

Show Tags

New post 15 Sep 2014, 23:35
2
1
Official Solution:

If \(x^2-100 \lt 300\) then \(x\) can take how many integer values?

A. 42
B. 39
C. 38
D. 37
E. 19


Given: \(x^2-100 \lt 300\);

\(x^2 \lt 400\);

\(|x| \lt 20\);

\(-20 \lt x \lt 20\), so \(x\) can take 39 integer values from -19 to 19, inclusive.


Answer: B
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Intern
Intern
avatar
S
Joined: 20 Jul 2012
Posts: 25
Reviews Badge
Re: M07-31  [#permalink]

Show Tags

New post 11 May 2016, 22:36
Bunuel wrote:
Official Solution:

If \(x^2-100 \lt 300\) then \(x\) can take how many integer values?

A. 42
B. 39
C. 38
D. 37
E. 19


Given: \(x^2-100 \lt 300\);

\(x^2 \lt 400\);

\(|x| \lt 20\);

\(-20 \lt x \lt 20\), so \(x\) can take 39 integer values from -19 to 19, inclusive.


Answer: B




One question here :-
can the above equation not be written as (x-20)(x+20) < 0
in that case the rang of x differs i.e x <20 or x <-20

I know i am missing some concept here (or worst some mistake) as x taking a value less than -20, just does not satisfy the give equation
_________________

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Mega collection of All RCs from GMAT, GRE & LSAT https://gmatclub.com/forum/mega-rc-collection-from-gmat-gre-lsat-273512.html
Mega collection of CRs from various sources (including LSAT) https://gmatclub.com/forum/mega-critical-reasoning-cr-collection-274044.html

Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7030
Re: M07-31  [#permalink]

Show Tags

New post 11 May 2016, 23:09
grsm wrote:
Bunuel wrote:
Official Solution:

If \(x^2-100 \lt 300\) then \(x\) can take how many integer values?

A. 42
B. 39
C. 38
D. 37
E. 19


Given: \(x^2-100 \lt 300\);

\(x^2 \lt 400\);

\(|x| \lt 20\);

\(-20 \lt x \lt 20\), so \(x\) can take 39 integer values from -19 to 19, inclusive.


Answer: B




One question here :-
can the above equation not be written as (x-20)(x+20) < 0
in that case the rang of x differs i.e x <20 or x <-20

I know i am missing some concept here (or worst some mistake) as x taking a value less than -20, just does not satisfy the give equation


Hi
you are correct in equation, BUT wrong in inference from it..
(x-20)(x+20)<0...
this means that x-20 and x+20 have to be of opposite sign...
this is possible in range from -20 to +20.....
check on your range x<-20...
put x as -21..
so (-21-20)(-21+20) = -41*-1= 41 which is >0 so range does not hold
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html


GMAT online Tutor

Intern
Intern
avatar
Joined: 09 Sep 2015
Posts: 5
Location: Grenada
GMAT 1: 630 Q46 V31
GPA: 3.53
WE: Education (Education)
Re M07-31  [#permalink]

Show Tags

New post 25 Jul 2016, 09:38
I think this is a high-quality question and I agree with explanation.
Manager
Manager
avatar
S
Joined: 23 Jul 2015
Posts: 156
GMAT ToolKit User
Re M07-31  [#permalink]

Show Tags

New post 05 Sep 2017, 19:42
I think this is a high-quality question and I agree with explanation.
Study Buddy Forum Moderator
User avatar
D
Joined: 04 Sep 2016
Posts: 1247
Location: India
WE: Engineering (Other)
Premium Member CAT Tests
Re: M07-31  [#permalink]

Show Tags

New post 03 Dec 2017, 14:36
niks18

Quote:
\(x^2 \lt 400\);

\(|x| \lt 20\);


I understood that \(\sqrt{}x^2 = |x|\) but
\(\sqrt{400}\) can take both values as -20 and +20
Why did we consider only positive values?
_________________

It's the journey that brings us happiness not the destination.

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50585
M07-31  [#permalink]

Show Tags

New post 03 Dec 2017, 19:49
adkikani wrote:
niks18

Quote:
\(x^2 \lt 400\);

\(|x| \lt 20\);


I understood that \(\sqrt{}x^2 = |x|\) but
\(\sqrt{400}\) can take both values as -20 and +20
Why did we consider only positive values?


Not clear what are you implying there.

\(\sqrt{400}=20\) ONLY, not +20 and -20. In contrast x^2 = 400 has TWO solutions, x = 20 and x = -20.

In the question above we DO consider the possibility of x being negative:
\(x^2 \lt 400\);

\(|x| \lt 20\)

\(x^2 \lt 400\);

\(-20 < x <20\)
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Study Buddy Forum Moderator
User avatar
D
Joined: 04 Sep 2016
Posts: 1247
Location: India
WE: Engineering (Other)
Premium Member CAT Tests
Re: M07-31  [#permalink]

Show Tags

New post 03 Dec 2017, 20:33
Bunuel

Thanks for your two cents

Quote:
Not clear what are you implying there.

\(\sqrt{400}=20\) ONLY, not +20 and -20. In contrast x^2 = 400 has TWO solutions, x = 20 and x = -20.


Is this because GMAT does not test imaginary roots ie complex number of the form \(\sqrt{-i}\)
_________________

It's the journey that brings us happiness not the destination.

Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 50585
Re: M07-31  [#permalink]

Show Tags

New post 03 Dec 2017, 20:37
adkikani wrote:
Bunuel

Thanks for your two cents

Quote:
Not clear what are you implying there.

\(\sqrt{400}=20\) ONLY, not +20 and -20. In contrast x^2 = 400 has TWO solutions, x = 20 and x = -20.


Is this because GMAT does not test imaginary roots ie complex number of the form \(\sqrt{-i}\)


GMAT deals with only Real Numbers: Integers, Fractions and Irrational Numbers.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Intern
Intern
User avatar
S
Joined: 05 Jan 2017
Posts: 40
GMAT ToolKit User
Re: M07-31  [#permalink]

Show Tags

New post 18 Oct 2018, 03:54
x^2−100<300
x^2 < 400
-20<x<20
so number of integers for x apart from 20 and -20 = 39
"B"
_________________

----------------------------
Kudos if my post helps!

GMAT Club Bot
Re: M07-31 &nbs [#permalink] 18 Oct 2018, 03:54
Display posts from previous: Sort by

M07-31

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  

Moderators: chetan2u, Bunuel



Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.