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

 It is currently 18 Sep 2018, 07:03

### 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

# What percent of the solution is water?

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 49204
What percent of the solution is water?  [#permalink]

### Show Tags

27 Jan 2017, 09:38
2
3
00:00

Difficulty:

55% (hard)

Question Stats:

62% (01:33) correct 38% (01:03) wrong based on 224 sessions

### HideShow timer Statistics

What percent of the solution is water?

(1) Adding 5 liters of water increases the percentage of water by 20%.
(2) There are 30 liters of solution before any additions or subtractions from the solution.

_________________
Intern
Joined: 08 Jan 2017
Posts: 27
Re: What percent of the solution is water?  [#permalink]

### Show Tags

28 Jan 2017, 14:44
assume there is W liter water in S liter of solution therefore (W/S)=?

1. assume there is W liter water in S liter solution the percentage is (W/S)*100 after adding a 5 liter of water there is S+5 liter of solution and W+5 of water. algebraically we can write (W+5)/(S+5)=(W/S)+.2* (20 percent increase is equal to .2) it is clear that there is no way to solve for w/s. insuff

2. S=30. clearly insufficient

1+2. having S=30 we can solve for w from * then W/S. Sufficient.
Director
Joined: 21 May 2013
Posts: 651
Re: What percent of the solution is water?  [#permalink]

### Show Tags

20 Feb 2017, 02:09
Bunuel wrote:
What percent of the solution is water?

(1) Adding 5 liters of water increases the percentage of water by 20%.
(2) There are 30 liters of solution before any additions or subtractions from the solution.

Bunuel,

Need your help here. Is option A not clear-I can get a unique solution in which we have 25 litres of water in a 30 litre solution and adding 5 litres increases the % of water by 20%.
Intern
Joined: 04 Dec 2017
Posts: 15
Re: What percent of the solution is water?  [#permalink]

### Show Tags

10 Apr 2018, 22:38
1
Bunuel wrote:
What percent of the solution is water?

(1) Adding 5 liters of water increases the percentage of water by 20%.
(2) There are 30 liters of solution before any additions or subtractions from the solution.

Initial conc. of water = W1 - To be found
Final conc. of water = W2
Initial volume of mixture = V1
Final volume of mixture = V2

Ci * Vi = Cf * Vf

St-1:
W1 = ?
W2 = 20%
V1 = ?
V2 = V1+5

W1 * V1 = 20 * (V1+5)

After simplification: W1 = 20 + (5/V1)

V1 can have multiple values. Hence, St-1 NS.

St-2:
W1 = ?
W2 = ?
V1 = 30
V2 = ?

W1 * 30 = W2 * V2
Hence, St-2 NS.

St-1 + St-2:
W1 = 20 + (5/V1)
V1 = 30

We get unique W1.

Therefore, answer is (C) (St-1 + St-2)
Director
Joined: 02 Oct 2017
Posts: 618
What percent of the solution is water?  [#permalink]

### Show Tags

Updated on: 04 Jul 2018, 21:46
Let x litre for one substance and y litre for water

I)(y+5)*100/x+y+5= y*100/x+y
Insufficient two unknowns

II)x+y=30 insufficient

Combining both statements
C

Another approach
As per statement 1
25 l of water addition would increase value by 100 percent
Means currently water is 25 but we don't know total volume of solution so insufficient

Statement 2 gives no info about water

Combining both we can get
25 l water is present in total 30 l of solution

Give kudos if it helps
Posted from my mobile device

Originally posted by push12345 on 22 Apr 2018, 05:00.
Last edited by push12345 on 04 Jul 2018, 21:46, edited 1 time in total.
Senior Manager
Joined: 14 Dec 2017
Posts: 471
Re: What percent of the solution is water?  [#permalink]

### Show Tags

03 Jun 2018, 04:56
Bunuel wrote:
What percent of the solution is water?

(1) Adding 5 liters of water increases the percentage of water by 20%.
(2) There are 30 liters of solution before any additions or subtractions from the solution.

Let P litres be the quantity of Initial solution, containing x litres of water.

hence % of water in Initial solution = $${(x/P) * 100}$$

Statement 1 says Adding 5 litres of water increases the % of water by 20%

Therefore New Quantity of Solution = (P+5) litres, containing (x+5) litres of water.

% Increase = $${(x+5)/(P+5)} - {(x/P)} = 20/100$$

we get an equation in 2 unknowns, hence St 1 alone is Insufficient.

Statement 2 says Quantity of Initial Solution, P = 30 litres, since no other info is provided, we can safely say St 2 alone is Insufficient.

Combining St 1 & 2

We can solve the equation in St 1, by substituting P = 30 & find value of x.

St 1 & 2 together are Sufficient.

Thanks,
GyM
_________________
Re: What percent of the solution is water? &nbs [#permalink] 03 Jun 2018, 04:56
Display posts from previous: Sort by

# Events & Promotions

 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®.