Question

A milk vendor has 2 cans of milk. The first contains 25% water and the rest milk. The
second contains 50% water. How much milk should he mix from each of the containers so
as to get 12 litres of milk such that the ratio of water to milk is 3: 5?​

Answer 1

Let the cost of 1 litre milk be Rs. 1

Milk in 1 litre mixture in 1st can = $$\frac{{3}}{{4}}$$ litre, C.P. of 1 litre mixture in 1st can Rs. $$\frac{{3}}{{4}}$$

Milk in 1 litre mixture in 2nd can = $$\frac{{1}}{{2}}$$ litre, C.P. of 1 litre mixture in 2nd can Rs. $$\frac{{1}}{{2}}$$

Milk in 1 litre of final mixture = $$\frac{{5}}{{8}}$$ litre, Mean price = Rs. $$\frac{{5}}{{8}}$$

By the rule of alligation, we have:

∴ Ratio of two mixtures = $$\frac{{1}}{{8}}$$ : $$\frac{{1}}{{8}}$$ = 1 : 1

So, quantity of mixture taken from each can = $$\left( {\frac{1}{2} \times 12} \right)$$ = 6 litres