It is currently 18 Jan 2018, 13:20

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

Events & Promotions in June
Open Detailed Calendar

How much pure alcohol should be added to 400ml of a 15% solu

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

Hide Tags

1 KUDOS received
Manager
Manager
User avatar
Joined: 22 Jul 2008
Posts: 95

Kudos [?]: 247 [1], given: 11

Location: Bangalore,Karnataka
How much pure alcohol should be added to 400ml of a 15% solu [#permalink]

Show Tags

New post 02 Dec 2009, 00:21
1
This post received
KUDOS
6
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  15% (low)

Question Stats:

83% (01:26) correct 17% (02:08) wrong based on 214 sessions

HideShow timer Statistics

How much pure alcohol should be added to 400ml of a 15% solution to make the strength of solution 32%?

A. 100 ml
B. 60 ml
C. 120 ml
D. 130 ml
E. 150 ml
[Reveal] Spoiler: OA

Kudos [?]: 247 [1], given: 11

Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2009
Posts: 281

Kudos [?]: 200 [0], given: 5

Location: India
Concentration: General Management
Re: Alcohol [#permalink]

Show Tags

New post 02 Dec 2009, 00:35
kirankp wrote:
How much pure alcohol should be added to 400ml of a 15% solution to make the strength of solution 32%?

A)100 ml
B) 60 ml
C)120 ml
D)130 ml
E)150 ml


400ml has 15% alcohol i.e 60ml . This means we have 340ml of water or the liquid with which alcohol is mixed
Let V be the volume of alcohol added to make the strength 32%
then V/340+V = 32/100. solving this we get V as 160ml

so we need to add 160 -60 = 100ml of alcohol

A-100ml

Kudos [?]: 200 [0], given: 5

2 KUDOS received
Intern
Intern
avatar
Joined: 31 Oct 2009
Posts: 38

Kudos [?]: 62 [2], given: 0

Re: Alcohol [#permalink]

Show Tags

New post 02 Dec 2009, 13:28
2
This post received
KUDOS
Here's how I did it:

\((400)(.15) = 60\) mL of Alcohol

\(.32 = \frac{60+x}{400+x}\)

\((.32)(400+x)=60+x\)

\(128+.32x=60+x\)

\(68=.68x\)

\(x=100\)

Kudos [?]: 62 [2], given: 0

Manager
Manager
avatar
Joined: 13 Aug 2009
Posts: 149

Kudos [?]: 337 [0], given: 7

WE 1: 4 years in IT
Re: Alcohol [#permalink]

Show Tags

New post 02 Dec 2009, 22:17
we can also go by answer choices

Tke 100 ml for eg

400 (old)+100 (new concentr)ml

500*32/100 = 160 ml (60ml is de old concentration +100 ml (newly added)

Let me know if im wrong :roll:

Cheers,
Raghav

Kudos [?]: 337 [0], given: 7

Senior Manager
Senior Manager
avatar
Joined: 30 Aug 2009
Posts: 281

Kudos [?]: 200 [0], given: 5

Location: India
Concentration: General Management
Re: Alcohol [#permalink]

Show Tags

New post 02 Dec 2009, 22:25
raghavs wrote:
we can also go by answer choices

Tke 100 ml for eg

400 (old)+100 (new concentr)ml

500*32/100 = 160 ml (60ml is de old concentration +100 ml (newly added)

Let me know if im wrong :roll:

Cheers,
Raghav


yes we can go by answer choices as well....but in GMAT we will see questions having values either in ascending or descending order unlike the options in the question here. Plugging in/POE is always suggested to be done taking the middle option first and then proceed.
I feel taking answer choices will take more time to solve this question.

Kudos [?]: 200 [0], given: 5

Manager
Manager
avatar
Joined: 09 May 2009
Posts: 203

Kudos [?]: 275 [0], given: 13

Re: Alcohol [#permalink]

Show Tags

New post 17 Dec 2009, 03:23
1
This post was
BOOKMARKED
kirankp wrote:
How much pure alcohol should be added to 400ml of a 15% solution to make the strength of solution 32%?

A)100 ml
B) 60 ml
C)120 ml
D)130 ml
E)150 ml


let xml is added
15% of 400=60 ml
after addition
(60+x)/(400+x)=32%
solving x=100 ml
_________________

GMAT is not a game for losers , and the moment u decide to appear for it u are no more a loser........ITS A BRAIN GAME

Kudos [?]: 275 [0], given: 13

VP
VP
avatar
P
Joined: 22 May 2016
Posts: 1247

Kudos [?]: 458 [0], given: 681

Premium Member CAT Tests
How much pure alcohol should be added to 400ml of a 15% solu [#permalink]

Show Tags

New post 19 Dec 2017, 13:45
kirankp wrote:
How much pure alcohol should be added to 400ml of a 15% solution to make the strength of solution 32%?

A. 100 ml
B. 60 ml
C. 120 ml
D. 130 ml
E. 150 ml

Let x = the amount of alcohol to be added
x = 100% alcohol = 1.00 (decimal percent)

Weighted average, slight variation.
For each part, A and B, to be mixed:

1) multiply its alcohol concentration (weight) by its volume

2) sum the separate results, which =

3) (Desired alcohol concentration of resultant solution) * (Volume of resultant solution, usually A + B)

.15(400) + 1(x) = .32(400 + x)

60 + x = 128 + .32x

.68x = 68

x = \(\frac{68}{.68}= 100\)

Answer A
_________________

At the still point, there the dance is. -- T.S. Eliot
Formerly genxer123

Kudos [?]: 458 [0], given: 681

Intern
Intern
avatar
B
Joined: 16 Jul 2016
Posts: 33

Kudos [?]: 10 [0], given: 2

Re: How much pure alcohol should be added to 400ml of a 15% solu [#permalink]

Show Tags

New post 19 Dec 2017, 13:59
Method 1:
Equation in terms of alcohol.
400(.15)+x(1.0)=(400+x)(.32)

60+x=128+.32x
.68x=68
x=100

Method 2: Equation in terms of water

.85(400)+x(0)=(.68)(400+x)

solving for x will give you the same answer.

Method 3- alligation

15____________32_____________100

68 17

4 1

the ratio of the 15 percent solution to pure alcohol = 4:1
Since there are 400 ml of the 15% solution, the multiplier is 100. 100(1)=100

Kudos [?]: 10 [0], given: 2

Intern
Intern
avatar
B
Joined: 16 Jul 2016
Posts: 33

Kudos [?]: 10 [0], given: 2

How much pure alcohol should be added to 400ml of a 15% solu [#permalink]

Show Tags

New post 19 Dec 2017, 14:00
Method 1:

Equation in terms of alcohol.

400(.15)+x(1.0)=(400+x)(.32)

60+x=128+.32x

.68x=68

x=100

Method 2: Equation in terms of water

.85(400)+x(0)=(.68)(400+x)

solving for x will give you the same answer.

Method 3- alligation

15____________32_____________100

68__________________________________ 17

4 _________________________________ 1

the ratio of the 15 percent solution to pure alcohol = 4:1
Since there are 400 ml of the 15% solution, the multiplier is 100. 100(1)=100

Method 4-Weighted average (in terms of alcohol)

[400(.15)+x]/[400+x]=32/100

Method 5-Weighted average (in terms of water)

[400(.85)]/[400+x]=68/100

Kudos [?]: 10 [0], given: 2

Director
Director
avatar
G
Joined: 07 Dec 2014
Posts: 884

Kudos [?]: 306 [0], given: 17

Re: How much pure alcohol should be added to 400ml of a 15% solu [#permalink]

Show Tags

New post 19 Dec 2017, 17:43
kirankp wrote:
How much pure alcohol should be added to 400ml of a 15% solution to make the strength of solution 32%?

A. 100 ml
B. 60 ml
C. 120 ml
D. 130 ml
E. 150 ml


let a=alcohol to be added
.15*400+a=.32(400+a)
a=100 ml
A

Kudos [?]: 306 [0], given: 17

Re: How much pure alcohol should be added to 400ml of a 15% solu   [#permalink] 19 Dec 2017, 17:43
Display posts from previous: Sort by

How much pure alcohol should be added to 400ml of a 15% solu

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


GMAT Club MBA Forum Home| About| Terms and Conditions| 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®.