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

It is currently 18 Dec 2018, 17:28

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 December
PrevNext
SuMoTuWeThFrSa
2526272829301
2345678
9101112131415
16171819202122
23242526272829
303112345
Open Detailed Calendar
  • Happy Christmas 20% Sale! Math Revolution All-In-One Products!

     December 20, 2018

     December 20, 2018

     10:00 PM PST

     11:00 PM PST

    This is the most inexpensive and attractive price in the market. Get the course now!
  • Key Strategies to Master GMAT SC

     December 22, 2018

     December 22, 2018

     07:00 AM PST

     09:00 AM PST

    Attend this webinar to learn how to leverage Meaning and Logic to solve the most challenging Sentence Correction Questions.

John wants to make a 100 ml of 5% alcohol solution mixing a quantity o

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

Hide Tags

Intern
Intern
avatar
B
Joined: 06 Aug 2015
Posts: 48
Concentration: General Management, Entrepreneurship
GMAT Date: 10-30-2016
GPA: 3.34
WE: Programming (Consulting)
Reviews Badge
John wants to make a 100 ml of 5% alcohol solution mixing a quantity o  [#permalink]

Show Tags

New post 09 Jun 2017, 10:28
1
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

73% (02:06) correct 27% (02:51) wrong based on 102 sessions

HideShow timer Statistics

John wants to make a 100 ml of 5% alcohol solution mixing a quantity of a 2% alcohol solution with a 7% alcohol solution. What are the quantities of each of the two solutions (2% and 7%) he has to use?

A) 60
B) 120
C) 30
D) 10
E) 90
Math Expert
User avatar
V
Joined: 02 Aug 2009
Posts: 7112
Re: John wants to make a 100 ml of 5% alcohol solution mixing a quantity o  [#permalink]

Show Tags

New post 09 Jun 2017, 10:41
HARRY113 wrote:
John wants to make a 100 ml of 5% alcohol solution mixing a quantity of a 2% alcohol solution with a 7% alcohol solution. What are the quantities of each of the two solutions (2% and 7%) he has to use?

A) 60
B) 120
C) 30
D) 10
E) 90


total qty = 100..
if avg is 5% and made from 2% and 7%, find the ratio of qty of each by weighted average method..
ratio of 2% = \(\frac{7-5}{7-2}=\frac{2}{5}\)..
so qty of 2% = \(100*\frac{2}{5}=40\)
and of 7% = 100-40=60..
A

HARRY113 you must be looking for qty of 7%..
otherwise qty of both has to be total that is 100
_________________

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

Senior SC Moderator
avatar
V
Joined: 22 May 2016
Posts: 2223
Premium Member CAT Tests
John wants to make a 100 ml of 5% alcohol solution mixing a quantity o  [#permalink]

Show Tags

New post 09 Jun 2017, 14:14
HARRY113 wrote:
John wants to make a 100 ml of 5% alcohol solution mixing a quantity of a 2% alcohol solution with a 7% alcohol solution. What are the quantities of each of the two solutions (2% and 7%) he has to use?

A) 60
B) 120
C) 30
D) 10
E) 90

Another way to do weighted average method.

Let A = the volume of the 5% solutions
Let B = the volume of the 2% solution

Volume of resultant mixture is given as 100 ml, so

A + B = 100, and
B = 100 - A

(strength of A)*(Vol of A) + (strength of B)*(Vol of B)
= (strength of resultant mixture)*(Vol of resultant mixture)

.07(A) + .02(B) = .05(100)

Substitute B = 100 - A:

.07(A) + .02(100 - A) = .05(100)

.07A + 2 - .02A = 5

.05A = 3

A = 60 mL and
B = (100 - A) = 40 mL

chetan2u wrote:
HARRY113 you must be looking for qty of 7%..
otherwise qty of both has to be total that is 100

Agreed. Answer A.
Director
Director
User avatar
D
Joined: 27 May 2012
Posts: 639
Premium Member
Re: John wants to make a 100 ml of 5% alcohol solution mixing a quantity o  [#permalink]

Show Tags

New post 05 Jul 2018, 09:49
1
HARRY113 wrote:
John wants to make a 100 ml of 5% alcohol solution mixing a quantity of a 2% alcohol solution with a 7% alcohol solution. What are the quantities of each of the two solutions (2% and 7%) he has to use?

A) 60
B) 120
C) 30
D) 10
E) 90


Can Moderator please correct this question ? We are looking for 7% solution and not BOTH 2% and 7% solution.
_________________

- Stne

Manager
Manager
avatar
S
Joined: 23 Nov 2017
Posts: 109
Location: Singapore
Concentration: Strategy, Other
GMAT 1: 660 Q49 V33
Re: John wants to make a 100 ml of 5% alcohol solution mixing a quantity o  [#permalink]

Show Tags

New post 22 Jul 2018, 22:59
HARRY113 wrote:
John wants to make a 100 ml of 5% alcohol solution mixing a quantity of a 2% alcohol solution with a 7% alcohol solution. What are the quantities of each of the two solutions (2% and 7%) he has to use?

A) 60
B) 120
C) 30
D) 10
E) 90


Isn't the question asks for both the solutions? (which would be 40 and 600) ?
GMAT Club Bot
Re: John wants to make a 100 ml of 5% alcohol solution mixing a quantity o &nbs [#permalink] 22 Jul 2018, 22:59
Display posts from previous: Sort by

John wants to make a 100 ml of 5% alcohol solution mixing a quantity o

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


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®.