Finding quantity of mixture

Question

In a mixture of milk and water, there is only $26$% water. After replacing the mixture with $7$ litres of pure milk, the percentage of milk in the mixture become $76$%. The quantity of mixture is

(a) 65 litre (b) 91 litre (c) 38 litre (d) 87 litre (e) none of these

ATTEMPT

Let mixture be of $x$ litres.Then water in mixture is $26x/100$ . After adding $7$ litres of milk in it ,it becomes $x+7$ litres and has $24$% water. So i get $24(x+7)/100 = 26x/100$ .Solving gives $x = 84$ .I am not sure though. Thanks for help

@EmilioNovati i cannot understand "mixture is replaced by 7 litres of pure milk" ? can you explain — Taylor Ted, Jul 25 '15 at 12:26

score 1 · Accepted Answer · answered Jul 25 '15 at 13:01

1

If we replace $7$ litres of the original mixture with $7$ litres of pure milk, we have that the final quantity of milk is: $$ \dfrac{74}{100}(x-7)+7=\dfrac{76}{100}x $$ Solving this equation we find $x$ that is the total (unchanged) quantity of mixture.

answered Jul 25 '15 at 13:01

Emilio Novati

62,675

I did not get how you got left hand side – Taylor Ted Jul 25 '15 at 13:38
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$74(x-7)/100$ is the quantity of milk from the remining original mixture. – Emilio Novati Jul 25 '15 at 14:11

Finding quantity of mixture

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