BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Target Test Prep · GMAT

Choose how you want to prepare

Learn live with an expert or move at your own pace. Every option includes the complete TTP study system.

★★★★★5.0559 reviews
GMATLiveTeach Starts Oct 17
Chris Peckover, Target Test Prep GMAT expert
LIVE ONLINE CLASSES

Get Ready for GMAT Test Day Faster with Live Online Classes

with Chris Peckover, 100th-Percentile GMAT Scorer

Oct 17 · Chris Peckover
Sat · 11:00 AM to 2:00 PM ET
Oct 20 · Chris Peckover
Tue, Thu · 8:00 to 10:00 PM ET
Oct 25 · Josh Braslow
Sun · 1:00 to 4:00 PM ET
Included
40 hours of live online classes + 6 months of TTP OnDemand
  • Attend the first class for free
  • Every class is recorded, so you never fall behind
View classes & enroll
Limited seats availableTarget Test Prep
EALiveTeachOnDemand 5 seats left Start anytime
EXECUTIVE ASSESSMENT

Target Test Prep EA OnDemand

Self-paced EA prep. Study on your schedule.

Logan Thompson
EXECUTIVE ASSESSMENT

Sep 6 to Dec 6, 2026

with Logan Thompson

165+ EA score guarantee
$05-day trial no automatic billing
Schedule
Sun · 9:30 AM to 12:30 PM ET
Included
40 hours of live online classes plus six months of access to the complete TTP EA OnDemand course.
  • 165+ EA Score Guarantee
  • 4,100+ Quant, Verbal, and Integrated Reasoning practice questions
  • 400+ hours of in-depth video lessons
  • 3,000+ step-by-step video solutions
View EA class & enroll Start free 5-day trial
Limited cohort · enrollment openTrial includes full course accessTarget Test Prep
GMATOnDemand Start anytime
SELF-PACED MASTERCLASS

Target Test Prep GMAT OnDemand

Complete access from day one. Study on your schedule.

715+ score guarantee
$0to start then $127/mo
  • Personalized study plan and analytics
  • Thousands of lessons and practice questions
Start free 5-day trial
Read 559 reviewsTarget Test Prep

Compare the format, schedule, and included access before enrolling. Prices and seat counts shown reflect the supplied offer details.

mixture

Expert replies
Post new topic Post Reply
Previous Topic Next Topic
Senior | Next Rank: 100 Posts
Posts: 70
Joined: Tue Jun 29, 2010 9:41 am
Thanked: 2 times
by taneja.niks » Mon May 30, 2011 12:03 pm
If there are 10 liters of a 20%-solution of alcohol, how much water should be added to reduce the concentration of alcohol in the solution by 75% ?
25 liters
27 liters
30 liters
32 liters
35 liters
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Source: — Problem Solving |
Senior | Next Rank: 100 Posts
Posts: 97
Joined: Sun May 15, 2011 9:19 amFollowed by: 1 member
Thanked: 18 times

by SoCan » Mon May 30, 2011 12:18 pm
The current solution has 2 liters of alcohol. If we want to reduce the concentration by 75%, we want to reduce the concentration from 20% to 5%. So:
2 liters of alcohol/(10 liters of original solution + x liters of water) = 0.05
2=0.5+0.05x
1.5=0.05x
30=x
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Legendary Member
Posts: 1309
Joined: Mon Apr 04, 2011 5:34 amFollowed by: 123 members
Location: India
Thanked: 310 times
GMAT Score:750

by cans » Mon May 30, 2011 12:22 pm
20% of 10 Litre solution => 2l alcohol.
reduce alcohol by 75% is same as keep alcohol by 25% = 20* 25/100 = 5%
Thus 5% of soln = 2 litre
100% = 40 litre
10 litre is already there and thus add 30 litre water more
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 70
Joined: Tue Jun 29, 2010 9:41 am
Thanked: 2 times

by taneja.niks » Mon May 30, 2011 12:23 pm
why 0.05?? shouldn it be 0.5???
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Senior | Next Rank: 100 Posts
Posts: 97
Joined: Sun May 15, 2011 9:19 amFollowed by: 1 member
Thanked: 18 times

by SoCan » Mon May 30, 2011 12:38 pm
taneja.niks wrote:why 0.05?? shouldn it be 0.5???
Why is the right side of the equation 0.05? Because that's the decimal equivalent of 5%. If you solve for 0.5, you're going to have a negative number - how much water you need to take out of the solution so that alcohol comprises 50%.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
Senior | Next Rank: 100 Posts
Posts: 79
Joined: Mon Jan 17, 2011 4:51 amFollowed by: 5 members
Location: Hyderabad, India
Thanked: 8 times

by galaxian » Mon May 30, 2011 12:39 pm
5% solution = 5/100 = .05 & not .5.
or you can say, 0.5 = 5/10 = 50 %
While, .05 = 5/100 = 5%.
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
User avatar
GMAT Instructor
Posts: 15539
Joined: Tue May 25, 2010 12:04 pmFollowed by: 1906 members
Location: New York, NY
Thanked: 13060 times
GMAT Score:790

by GMATGuruNY » Mon May 30, 2011 7:53 pm
taneja.niks wrote:If there are 10 liters of a 20%-solution of alcohol, how much water should be added to reduce the concentration of alcohol in the solution by 75% ?
25 liters
27 liters
30 liters
32 liters
35 liters
Amount of alcohol in the original solution = .2*10 = 2 liters.
A 20% concentration reduced by 75% = 20 - .75*20 = 5%.
Thus, the 2 liters of alcohol must be 5% of the final mixure:
2 = .05x
x = 40 liters.

Since 40 liters are needed and the original mixture is 10 liters, the amount of water added = 40-10 = 30 liters.

The correct answer is C.
Private tutor exclusively for the GMAT and GRE, with over 20 years of experience.
Followed here and elsewhere by over 1900 test-takers.
I have worked with students based in the US, Australia, Taiwan, China, Tajikistan, Kuwait, Saudi Arabia -- a long list of countries.
My students have been admitted to HBS, CBS, Tuck, Yale, Stern, Fuqua -- a long list of top programs.

As a tutor, I don't simply teach you how I would approach problems.
I unlock the best way for YOU to solve problems.

For more information, please email me (Mitch Hunt) at [email protected].
Student Review #1
Student Review #2
Student Review #3
Top
Join the discussion
Log in to postLogin with Googleuse password
QUOTE IN REPLY
Post new topic Post Reply
• Page 1 of 1