Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 16 Sep 2014, 01:46

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# How many liters of pure alcohol must be added to a 100-liter

Author Message
TAGS:
Director
Joined: 17 Dec 2005
Posts: 555
Location: Germany
Followers: 1

Kudos [?]: 8 [0], given: 0

How many liters of pure alcohol must be added to a 100-liter [#permalink]  29 Dec 2005, 09:23
00:00

Difficulty:

(N/A)

Question Stats:

100% (01:03) correct 0% (00:00) wrong based on 0 sessions
19. How many liters of pure alcohol must be added to a 100-liter solution that is 20 percent alcohol in order to produce a solution that is 25 percent alcohol?

B) 20/3

Please show me how to solve, I've lost some piece of brain.
Manager
Joined: 11 Aug 2005
Posts: 84
Followers: 1

Kudos [?]: 5 [0], given: 0

20% of 100 litres = 20 litres alcohol
80 litres water
let x litres alcohol be added.

the ratio of alcohol to total solution = strength of the solution = 25%

(20+x)/(100+x)=0.25

solve this to get ur answer as 20/3
_________________

------------------------------

only if i could choose....

Manager
Joined: 15 May 2005
Posts: 81
Followers: 1

Kudos [?]: 0 [0], given: 0

Let X be litres of pure alcohol that must be added. Since it is pure alcohol, the percent of alochol in it would be 100%

The sum of (Percentage of Alcohol * quantity for each of the parts) must satisfy the given condition

Therefore you can setup an equation

100 * X + 20 * 100 = 25 * (100 + X )

Solving for X, X = 20/3

Not sure if my explanation was any good ... let me know if you need to me to clarify any specifics
Director
Joined: 17 Dec 2005
Posts: 555
Location: Germany
Followers: 1

Kudos [?]: 8 [0], given: 0

Thank you crazyfin and 5elements. Now it's clear.
Senior Manager
Joined: 11 Nov 2005
Posts: 336
Location: London
Followers: 1

Kudos [?]: 8 [0], given: 0

20/3

the idea is to balance the volume and % of alcohol on both sides. (before dilution and after dilution)
CEO
Joined: 21 Jan 2007
Posts: 2770
Location: New York City
Followers: 7

Kudos [?]: 230 [0], given: 4

crazyfin wrote:
20% of 100 litres = 20 litres alcohol
80 litres water
let x litres alcohol be added.

the ratio of alcohol to total solution = strength of the solution = 25%

(20+x)/(100+x)=0.25

solve this to get ur answer as 20/3

(20+x)/(100+x)=0.25
(20+x) = 0.25(100+x)
20+x = 25 + .25x
20+1x = 25 + .25x
.75x = 5

x= 5/.75 = 20/3
Similar topics Replies Last post
Similar
Topics:
1 How many liters of pure alcohol must be added to a 100-liter 5 31 Mar 2011, 09:25
How many ounces of pure water must be added to 50 ounces of 3 10 Dec 2007, 15:00
How many ounces of pure water must be added to 50 ounces of 5 02 Nov 2007, 15:59
How many liters of pure alcohol must be added to a 100 liter 4 26 Jul 2007, 18:47
How many liters of a solution that is 15% salt must be added 12 09 Oct 2006, 16:55
Display posts from previous: Sort by