The ratio of acid and water in solution A is 5 : 4 and 7 : 11 in solution B. 10 liters of A is mixed with 8 liters of B. In 324 ml of the resulting solution, how much water (in ml) should be added to get a solution containing 3313% acid?

A shopkeeper mixes two types of rice in the ratio 5 : 3, where one type costs ₹75 per kg and the other costs ₹85 per kg. Find the average price per kg of the mixture.

In what ratio (cheaper to dearer) should a grocer mix two varieties of pulses costing ₹18 and ₹22 per kg, respectively, to obtain a mixture worth ₹19.50 per kg?