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

 It is currently 24 May 2015, 14:30

### 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:
Manager
Joined: 08 Sep 2006
Posts: 53
Followers: 0

Kudos [?]: 10 [0], given: 0

How many liters of pure alcohol must be added to a 100 liter [#permalink]  26 Jul 2007, 18:47
How many liters of pure alcohol must be added to a 100 liter solution that is 20% alcohol in order to produce a solution that is 25% alcohol?

a)7/2
b)5
c)20/3
d)8
e)39/4

Thanks,
Senior Manager
Joined: 28 Jun 2007
Posts: 463
Followers: 2

Kudos [?]: 6 [0], given: 0

It has to be atleast above 5. So 1 and 2 ruled out

28/108 is too high and that would rule out the other option E too.

so by POE, it must be C.

26.66/106.66 sounds right too.
GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5077
Location: Singapore
Followers: 22

Kudos [?]: 186 [0], given: 0

100 litres -> 20% = alcohol = 20 litres alcohol

Add x litres. So now total = (100+x)litres.

25/100 * (100+x) = 20+x
25 + 0.25x = 20+x
5 = 0.75x
x = 20/3
Manager
Joined: 05 Feb 2007
Posts: 141
Followers: 1

Kudos [?]: 7 [0], given: 7

a slightly different approach [#permalink]  17 Nov 2007, 19:37
I did this in a slightly different way :

|100-25| = 75
|20-25| = 5

5:75 reduces to 1:15

15/16 = 100/x

x= 106 2/3

106 2/3 - 100 = 6 2/3

6 2/3 = 20/3
Director
Joined: 09 Aug 2006
Posts: 765
Followers: 1

Kudos [?]: 72 [0], given: 0

ywilfred wrote:
100 litres -> 20% = alcohol = 20 litres alcohol

Add x litres. So now total = (100+x)litres.

25/100 * (100+x) = 20+x
25 + 0.25x = 20+x
5 = 0.75x
x = 20/3

Solved it the same way to get C.
Similar topics Replies Last post
Similar
Topics:
10 How many liters of water must be evaporated from 50 liters of a 3-perc 11 26 Nov 2014, 06:47
1 How many liters of pure alcohol must be added to a 100-liter 6 31 Mar 2011, 09:25
How many liters of a solution that 15% salt must be added to 1 13 Mar 2007, 18:49
How many liters of a solution that is 15% salt must be added 12 09 Oct 2006, 16:55
How many liters of pure alcohol must be added to a 100-liter 5 29 Dec 2005, 09:23
Display posts from previous: Sort by