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

 It is currently 26 Apr 2019, 00:56

### 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

# A factory cleans its machinery with a solution that is 87% water and

Author Message
TAGS:

### Hide Tags

Senior Manager
Joined: 06 Jul 2016
Posts: 364
Location: Singapore
Concentration: Strategy, Finance
A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

22 Jun 2017, 23:01
6
00:00

Difficulty:

45% (medium)

Question Stats:

72% (02:36) correct 28% (02:59) wrong based on 237 sessions

### HideShow timer Statistics

A factory cleans its machinery with a solution that is 87% water and the remainder vinegar. If the factory manager starts with 260 Litres of a 40% vinegar solution, how much water must the manager add to the existing solution to attain the proper vinegar concentration for cleaning the machinery?

A) 104 Litres
B) 120 Litres
C) 470 Litres
D) 540 Litres
E) 800 Litres

_________________
Put in the work, and that dream score is yours!
Senior Manager
Joined: 28 May 2017
Posts: 283
Concentration: Finance, General Management
Re: A Factory Cleans its machinery with  [#permalink]

### Show Tags

22 Jun 2017, 23:16
2
akshayk wrote:
A factory cleans its machinery with a solution that is 87% water and the remainder vinegar. If the factory manager starts with 260 Litres of a 40% vinegar solution, how much water must the manager add to the existing solution to attain the proper vinegar concentration for cleaning the machinery?

A) 104 Litres
B) 120 Litres
C) 470 Litres
D) 540 Litres
E) 800 Litres

Vinegar content in Ideal Solution should be - 13%
Vinegar content is given solution - 260 x 40%
Total volume of the solution = 260 x 40 x 100/13 = 800
Water that need to be added = 800-260 = 540

_________________
If you like the post, show appreciation by pressing Kudos button
Senior SC Moderator
Joined: 22 May 2016
Posts: 2654
A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

23 Jun 2017, 09:04
akshayk wrote:
A factory cleans its machinery with a solution that is 87% water and the remainder vinegar. If the factory manager starts with 260 Litres of a 40% vinegar solution, how much water must the manager add to the existing solution to attain the proper vinegar concentration for cleaning the machinery?

A) 104 Litres
B) 120 Litres
C) 470 Litres
D) 540 Litres
E) 800 Litres

We have a solution that is 40% vinegar. We need to add water, which is 0% vinegar, to obtain a resultant solution that is 13% vinegar.

Let A = solution with 40% vinegar

Let w = amount of water to be added

A + w = Total volume of resultant mixture

Water is 0% vinegar.

(Concen. of A)(Vol of A) + (Concen. of w)(Vol of w) = (Desired concen. of resultant solution)(Vol of resultant solution)

.40(A) + (0)w = .13(A + w)

.40(240) + 0w = .13(240 + w)

104 + (0)w = (.13)(240) + .13w

104 = 33.8 + .13w

70.2 = .13w

7020 = 13W

w = 540

_________________
Listen, are you breathing just a little, and calling it a life?
-- Mary Oliver

For practice SC questions with official explanations that were posted and moderated by the SC Team,
go to SC Butler here: https://gmatclub.com/forum/project-sc-butler-get-2-sc-questions-everyday-281043.html
VP
Joined: 07 Dec 2014
Posts: 1179
Re: A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

23 Jun 2017, 10:57
2
1
akshayk wrote:
A factory cleans its machinery with a solution that is 87% water and the remainder vinegar. If the factory manager starts with 260 Litres of a 40% vinegar solution, how much water must the manager add to the existing solution to attain the proper vinegar concentration for cleaning the machinery?

A) 104 Litres
B) 120 Litres
C) 470 Litres
D) 540 Litres
E) 800 Litres

.6*260+w=.87(260+w)
w=540 liters
D
Manager
Joined: 30 May 2012
Posts: 201
Location: United States (TX)
Concentration: Finance, Marketing
GPA: 3.3
WE: Information Technology (Consulting)
Re: A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

12 Jul 2017, 09:27
Can someone help me with this question? I am unable to understand the solutions provided. Thanks
p.s: Is this a mixture problem?
Senior Manager
Joined: 28 Jun 2015
Posts: 290
Concentration: Finance
GPA: 3.5
Re: A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

12 Jul 2017, 10:19
1
1
Let $$x$$ be the amount of water to be added to the solution.

The 260 litre solution contains 60% water, so $$\frac{260*60}{100} = 156$$

$$\frac{156+x}{260+x} = \frac{87}{100}$$

$$15600 + 100x = 22620 + 87x$$

$$13x = 7020$$

$$x = 540$$. Ans - D.
_________________
I used to think the brain was the most important organ. Then I thought, look what’s telling me that.
Intern
Joined: 09 Jan 2017
Posts: 1
Re: A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

12 Jul 2017, 10:39
From allegation- (40-13):(13-0)=X:260 on solving, X=540

Sent from my XT1562 using GMAT Club Forum mobile app
Target Test Prep Representative
Status: Founder & CEO
Affiliations: Target Test Prep
Joined: 14 Oct 2015
Posts: 5871
Location: United States (CA)
Re: A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

16 Jul 2017, 17:23
1
akshayk wrote:
A factory cleans its machinery with a solution that is 87% water and the remainder vinegar. If the factory manager starts with 260 Litres of a 40% vinegar solution, how much water must the manager add to the existing solution to attain the proper vinegar concentration for cleaning the machinery?

A) 104 Litres
B) 120 Litres
C) 470 Litres
D) 540 Litres
E) 800 Litres

We need the vinegar solution to be 13% vinegar.

We have 260 litres that contain 0.4(260) = 104 litres of vinegar.

We can let x = the number of litres of water to be added and create the following equation:

104/(260 + x) = 13/100

10,400 = 13(260 + x)

10,400 = 3,380 + 13x

7,020 = 13x

540 = x

_________________

# Scott Woodbury-Stewart

Founder and CEO

Scott@TargetTestPrep.com
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

Intern
Joined: 28 Dec 2010
Posts: 23
A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

Updated on: 18 Jul 2017, 20:21
Another way to look at the problem:

Initial Solution:

Volume of water = 260 *60/100 = 156 litres ---(1)

Let the volume of water to be added = x litres ---(2)

Final Solution: (Given in the problem)

Volume of water in the final solution = 87% = 87/100

We can represent the percentage of water in the final solutions as:

(156 + x)/(260+x) = 87/100

15600 + 100x = 87*260 +87x
15600 - 22620 = 87x - 100x
- 7020 = -13x
x = 540
Attachments

mixtureproblem.jpg [ 18.32 KiB | Viewed 1432 times ]

Originally posted by gary391 on 18 Jul 2017, 18:00.
Last edited by gary391 on 18 Jul 2017, 20:21, edited 1 time in total.
Intern
Joined: 28 Dec 2010
Posts: 23
A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

18 Jul 2017, 18:06
1
Alligation approach:
Attachments

File comment: Alligation Approach:

mixtureproblemusingaligation.JPG [ 36.01 KiB | Viewed 1448 times ]

VP
Joined: 09 Mar 2016
Posts: 1282
Re: A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

19 Jul 2017, 05:03
1
[quote="Blackbox"]Can someone help me with this question? I am unable to understand the solutions provided. Thanks
p.s: Is this a mixture problem?

hi. let me try to explain. to have optimal proportion of mixture with two liquids: water must be 87% of the total solution, while vinegar must be 13% of the total solution. we have total solution which is 260 liters. 40 % of 260 = 104 is vinegar. the rest is water (260-104 = 156) now we are asked how much more water do we need to have 13 % of vinegar and 87 % of water. now we can use simple proportional method 13/87 = 104/x cross multiply and x = 696. since 156 liters of water is already there we need to subtract 696-156 = 540 YAY ! here is answer!!

is it clear ?

have a great day
Intern
Joined: 09 Dec 2013
Posts: 27
Re: A factory cleans its machinery with a solution that is 87% water and  [#permalink]

### Show Tags

21 Jul 2017, 22:34
ScottTargetTestPrep wrote:
akshayk wrote:
A factory cleans its machinery with a solution that is 87% water and the remainder vinegar. If the factory manager starts with 260 Litres of a 40% vinegar solution, how much water must the manager add to the existing solution to attain the proper vinegar concentration for cleaning the machinery?

A) 104 Litres
B) 120 Litres
C) 470 Litres
D) 540 Litres
E) 800 Litres

We need the vinegar solution to be 13% vinegar.

We have 260 litres that contain 0.4(260) = 104 litres of vinegar.

We can let x = the number of litres of water to be added and create the following equation:

104/(260 + x) = 13/100

10,400 = 13(260 + x)

10,400 = 3,380 + 13x

7,020 = 13x

540 = x

Can you please explain how did you form this equation?
104/(260 + x) = 13/100
Thanks
Re: A factory cleans its machinery with a solution that is 87% water and   [#permalink] 21 Jul 2017, 22:34
Display posts from previous: Sort by