Liquids A, B, and C contain 20%, 50%, and 80%

Question

Liquids A, B, and C contain 20%, 50%, and 80% alcohol respectively. The three liquids are mixed in a ratio of 1:2:2 and the resultant solution is mixed with pure alcohol in a ratio of 1:1. What will be the percentage of alcohol in this final solution?

A. 56%
B. 64%
C. 72%
D. 78%
E. 84%

A. 56%
B. 64%
C. 72%
D. 78%
E. 84%

Krunaal · Accepted Answer

Alcohol in (1 + 2 + 2) ml => 5 ml mixed solution will be (0.2 + 1 + 1.6) ml => 2.8 ml

Now it is mixed with 5 ml of pure alcohol solution, the total alcohol content of this solution will be 2.8 + 5 = 7.8 ml => 7.8/10 =  78%

Answer D

BraydinWalters · Answer

Let's first realize that the 100% alcohol is also just another ratio in the overall mixture.

We're mixing 5 parts (1:2:2) and then mixing those 1:1 with 100% alcohol.

Because of this, the total ration can be seen as 1:2:2:5 (5 because the first mixture adds up to 5 parts)

Now multiply each percentage by it's number of parts and divide these by the total number of parts (1+2+2+5= 10 )

1(20) + 2(50) + 2(80) + 5(100) = 780

780 / 10 = 78

So  78% or D is your answer .

HarshavardhanR · Answer

https://gmatclub.com/forum/download/file.php?id=83851 Harsha GMAT-Club-Forum-pct1dn84.png

Bunuel · Answer

Experts' Global Video Solution:

https://www.youtube.com/watch?v=JGwIwyjw41s

Aboyhasnoname · Answer

Let's Assume we take 10 Litres of Drink A.... 
So we have to take 20 Litres of B and 20 Litres of C 
The Alcohol in them as below 
   DRINK 
 ALCHOHOL 
 Amount

A (10 Litres) 
 20% 
 2 Litres

B (20 Litres) 
 50% 
 10 Litres

C (20 Litres) 
 80% 
 16 Litres

TOTAL = 50 LITRES 
  
 28 LITRES

NOW WE ADD 50 LITRES MORE ALCOHOL ..SO NEW ALCOHOL 78 AND NEW TOTAL IS 100...So 78%

ShahriarArnob · Answer

Let assume the mixed ratio by multiplying the ratio with 100, 100:200:200. Thus the alcohol is the previous solution is 20+50*2+80*2=280.
Thus the resultant solution is 500 with alcohol 280. Now if we add pure alcohol with a ratio 1:1 (pure alcohol : resultant solution) and the pure alcohol must be 500. The final solution will be 500+500=1000 and the alcohol will be 280+500=780. Now the percentage becomes, 780*100/1000=78%

Liquids A, B, and C contain 20%, 50%, and 80%

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DRINK	ALCHOHOL	Amount
A (10 Litres)	20%	2 Litres
B (20 Litres)	50%	10 Litres
C (20 Litres)	80%	16 Litres
TOTAL = 50 LITRES		28 LITRES

GMAT Problem Solving (PS) Questions

Liquids A, B, and C contain 20%, 50%, and 80%

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