d Word Problem 17 (Partial percentage, mixture) | Job Exam Rare Mathematics (JEMrare) - Solved MCQs

# Word Problem 17 (Partial percentage, mixture)

Problem 17 : A mixture of 70 liters of milk and water contains 10% water. How much water must be added to make water 12-1/2 % ?

a) 10                b) 5                      c) 2                    d) 12

Solution:

Let y liters of water be added to make water 12.5 %

$Then Quantity Of Water = (7+y) Liters$

And

$Quantity Of Mixture = (70+y) Liters$

New concentration of water in the mixture can be expressed as ;

$New Concentration = \frac{water}{Mixture}\times 100$

This gives;

$y+7 = \frac{12.5} {100} \times70$

So we get;

$12.5(70+y)=(7+y) \times100$

or

$875+12.5y=700+100y$

or

$875-700=100y-12.5y$

or

$175=87.5y$

or

$y= \frac {175}{87.5}=2 Liters$

So, two liters of water should be added to make concentration of water to be 12-1/2% or 12.5 %

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