How many litres of solutions having 30% milk and 70% milk should be mi

Question

How many litres of solutions having 30% milk and 70% milk should be mixed so that we get 40 litres of 45% milk solution?

A. 10, 30 
B. 12, 28 
C. 15, 25 
D. 20, 20 
E. 25, 15

firas92 · Answer

\frac{W_a}{W_b} = \frac{Avg_b-Avg_{overall}}{Avg_{overall}-Avg_a}

\frac{W_a}{W_b} = \frac{70-45}{45-30} = \frac{25}{15}

Answer is  (E)

satavishamitra · Answer

Let's assume the weight of Solution A to be - A
And it's mentioned that the final solution has A and B and together they make 40 litres.
So, weight of B would be = 40-A

Let's create a table to help us with visualisation

Content  % Milk  Litres  Total  
  A  30%  A  30% of A  
  B  70%  40 - A  70% of (40 - A)  
  Final Mixture  45%  40  45% of 40

Now let's create the final equation:

30% of A + 70% of B = % and litres of the final solution 
.30(A) + .70(40-A) = .45*40
A = 25

So, weight of A= 25 litres
And weight of B = 40-A i.e. 40-25 = 15 litres

Correct answer 25,15

How many litres of solutions having 30% milk and 70% milk should be mi

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Content	% Milk	Litres	Total
A	30%	A	30% of A
B	70%	40 - A	70% of (40 - A)
Final Mixture	45%	40	45% of 40

GMAT Problem Solving (PS) Questions

How many litres of solutions having 30% milk and 70% milk should be mi

Prep Toolkit

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My Rewards