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

It is currently 17 Jan 2019, 15:23

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 January
PrevNext
SuMoTuWeThFrSa
303112345
6789101112
13141516171819
20212223242526
272829303112
Open Detailed Calendar
  • The winning strategy for a high GRE score

     January 17, 2019

     January 17, 2019

     08:00 AM PST

     09:00 AM PST

    Learn the winning strategy for a high GRE score — what do people who reach a high score do differently? We're going to share insights, tips and strategies from data we've collected from over 50,000 students who used examPAL.
  • Free GMAT Strategy Webinar

     January 19, 2019

     January 19, 2019

     07:00 AM PST

     09:00 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.

If a portion of a half water/half alcohol mix is replaced

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

Hide Tags

 
Manager
Manager
avatar
G
Joined: 09 Jun 2014
Posts: 218
Location: India
Concentration: General Management, Operations
Schools: Tuck '19
Premium Member Reviews Badge
Re: If a portion of a half water/half alcohol mix is replaced  [#permalink]

Show Tags

New post 27 Oct 2018, 21:44
zest4mba wrote:
If a portion of a half water/half alcohol mix is replaced with 25% alcohol solution, resulting in a 30% alcohol solution, what percentage of the original alcohol was replaced?

A. 3%
B. 20%
C. 66%
D. 75%
E. 80%




Let the volume of solution be 100 ml

Given its a 50% water/505 alcohol solution.

So Alcohol=50ml and water = 50 ml

Now

50-0.50x(removing "x" ml of 50 % alcohol solution) + 0.25x(replacing with 25% alcohol solution) = 30(30%alcohol solution)

X= 80 ml

clearly origininal solution was 100 ml so its 80%

ALTERNATIVE APPROACH

Weighted average

We have 25 - 30 - 50 % alcohol solution

Ratio of 25% alcohol solution to 50% alchohol solution (W1/W2) = 50-30 / 30-25 = 4/1

Therefore we have 4 units of alcohol sulution of of 5 units of net solution
impues 4/5= 80%

Press Kudos if it helps!!

Senior Manager
Senior Manager
avatar
G
Joined: 27 Dec 2016
Posts: 275
CAT Tests
Re: If a portion of a half water/half alcohol mix is replaced  [#permalink]

Show Tags

New post 25 Dec 2018, 16:57
gmat1011 wrote:
Hi Financier

It will work if you consider it as follows:

50% ---------------- 25%

------------30%---------

5%------------------20%

so ratio is 1:4 in final mixture

Earlier type 1 alcohol was 1

Now it is 1/5 ----> so loss of 4/5 = 80%...


Could someone please explain where 1/5 is coming from towards the end? I have been trying to figure out since past 30 mins but I haven't had any luck. Would immensely appreciate it!
GMAT Club Bot
Re: If a portion of a half water/half alcohol mix is replaced &nbs [#permalink] 25 Dec 2018, 16:57

Go to page   Previous    1   2   3   [ 42 posts ] 

Display posts from previous: Sort by

If a portion of a half water/half alcohol mix is replaced

  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®.