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

It is currently 16 Jul 2018, 03:56

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

90 students represent x percent of the boys at Jones Element

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

Hide Tags

1 KUDOS received
Intern
Intern
avatar
Joined: 06 Dec 2012
Posts: 1
90 students represent x percent of the boys at Jones Element [#permalink]

Show Tags

New post Updated on: 07 Jan 2013, 02:46
1
4
00:00
A
B
C
D
E

Difficulty:

  45% (medium)

Question Stats:

66% (01:24) correct 34% (01:25) wrong based on 278 sessions

HideShow timer Statistics

90 students represent x percent of the boys at Jones Elementary School. If the boys at Jones Elementary make up 40% of the total school population of x students, what is x?

A. 125
B. 150
C. 225
D. 250
E. 500

[cant understand the language]

Originally posted by vidyavatigore on 06 Jan 2013, 10:31.
Last edited by Bunuel on 07 Jan 2013, 02:46, edited 1 time in total.
Renamed the topic and edited the question.
1 KUDOS received
VP
VP
User avatar
Status: Been a long time guys...
Joined: 03 Feb 2011
Posts: 1264
Location: United States (NY)
Concentration: Finance, Marketing
GPA: 3.75
GMAT ToolKit User Premium Member
Re: percent [#permalink]

Show Tags

New post 06 Jan 2013, 10:39
1
vidyavatigore wrote:
90 students represent x percent of the boys at Jones Elementary School. If the boys at Jones Elementary make up 40% of the total school population of x students, what is x?

[cant understand the language]

125

150

225

250

500


\(90=x/100 * # boys\)
#boys=\(0.4x\)
\(90=x/100 * 0.4x\).
\(9000=0.4* x^2\)
\(22500=x^2\)
\(x=150\)
answer=150.
_________________

Prepositional Phrases Clarified|Elimination of BEING| Absolute Phrases Clarified
Rules For Posting
www.Univ-Scholarships.com

Expert Post
3 KUDOS received
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 47015
Re: 90 students represent x percent of the boys at Jones Element [#permalink]

Show Tags

New post 07 Jan 2013, 02:56
3
1
vidyavatigore wrote:
90 students represent x percent of the boys at Jones Elementary School. If the boys at Jones Elementary make up 40% of the total school population of x students, what is x?

A. 125
B. 150
C. 225
D. 250
E. 500

[cant understand the language]


Step by step:
90 students represent x percent of the boys at Jones Elementary School: \(90=\frac{x}{100}*boys\) --> \(boys=\frac{9000}{x}\);

The boys at Jones Elementary make up 40% of the total school population of x students: \(boys=0.4x\) --> \(\frac{9000}{x}=0.4x\) --> \(x=150\).

Answer: B.

To elaborate: there are total of 150 students at the school and 0.4*150=60 of them are boys. 150% of 60 boys is 90.
_________________

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

Manager
Manager
avatar
B
Joined: 17 Aug 2015
Posts: 102
GMAT ToolKit User
Re: 90 students represent x percent of the boys at Jones Element [#permalink]

Show Tags

New post 28 Aug 2016, 08:36
backsolve some answer choices :--
let us take x= 500 , 40% of these represents boys . Ok this implies boys = 200. But does 500% of 200 = 90? 500% of 200 =1000. so this does not work. Actually this tells us that we need something small.

let us take x=150. 40% of 150 = 60 . So boys = 60. 150% of boys = 3/2*60 = 90!. This works.

**********************************
Using algebra
90=x/100*40/100*x=>x^2 = 9*10000/4 = > x = 300/2 => x = 150!
Director
Director
avatar
S
Joined: 12 Nov 2016
Posts: 774
Location: United States
Schools: Yale '18
GMAT 1: 650 Q43 V37
GRE 1: 315 Q157 V158
GPA: 2.66
Re: 90 students represent x percent of the boys at Jones Element [#permalink]

Show Tags

New post 07 Jun 2017, 16:13
vidyavatigore wrote:
90 students represent x percent of the boys at Jones Elementary School. If the boys at Jones Elementary make up 40% of the total school population of x students, what is x?

A. 125
B. 150
C. 225
D. 250
E. 500

[cant understand the language]


The key to understanding this question is understanding that x is constant- in other words- the total number of students as represented by X must equal the the percentage of increase of some number must be to equal 90.

150 (.4) = 60 boys

90= 60 boys (150%) (naturally, applying real world thinking, we might typically think that the actual number of boys would be some number greater than 90 but we could perhaps rationalize the practicality of this problem with the following example- if a certain school needs to expand it's population of minority students to a certain percentage increase of minority students at that school).

90 boys represent 150% of the boys at this high- it's kind of a weird question - also it's important to note a 150% increase of some number is NOT equal to 150% of that number
Intern
Intern
avatar
B
Joined: 09 Oct 2016
Posts: 35
Re: 90 students represent x percent of the boys at Jones Element [#permalink]

Show Tags

New post 28 Jul 2017, 08:48
vidyavatigore wrote:
90 students represent x percent of the boys at Jones Elementary School. If the boys at Jones Elementary make up 40% of the total school population of x students, what is x?

A. 125
B. 150
C. 225
D. 250
E. 500

[cant understand the language]


#of Boys = X(40/100)
90 = (X/100)(40X/100)
90 = ((4X^2)/ 1000)
X^2 = 90000/4 ---- take the root square for both sides
X= 300/4
X = 150
Director
Director
User avatar
D
Joined: 04 Dec 2015
Posts: 700
Location: India
Concentration: Technology, Strategy
Schools: ISB '19, IIMA , IIMB, XLRI
WE: Information Technology (Consulting)
GMAT ToolKit User
Re: 90 students represent x percent of the boys at Jones Element [#permalink]

Show Tags

New post 18 Aug 2017, 23:14
vidyavatigore wrote:
90 students represent x percent of the boys at Jones Elementary School. If the boys at Jones Elementary make up 40% of the total school population of x students, what is x?

A. 125
B. 150
C. 225
D. 250
E. 500

[cant understand the language]

\(90\) students represent \(x\) percent of the boys at Jones Elementary School.

\(90 = x\)% of Boys \(= (\frac{x}{100})\) Boys ------ (i)

Boys at Jones Elementary make up \(40\)% of the total school population of \(x\) students.

Boys \(= 40\)% of \(x = (\frac{40}{100})x\)

Boys \(= (\frac{2}{5})x\) ------- (ii)

Substituting Value of Boys from (ii) into (i), we get;

\(90 = (\frac{x}{100}) (\frac{2}{5})x\)

\(\frac{(x^2)(2)}{(100)(5)} = 90\)

\(x^2 = \frac{(90)(100)(5)}{2} = 45*5*100\)

\(x = \sqrt{45*5*100} = 3*5*10 = 150\)

Answer (B)...
Re: 90 students represent x percent of the boys at Jones Element   [#permalink] 18 Aug 2017, 23:14
Display posts from previous: Sort by

90 students represent x percent of the boys at Jones Element

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

Events & Promotions

PREV
NEXT


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®.