**1.**A cask contains alcohol solution with concentration 18%. If 6 Liters of this mixture is taken out and replaced with water, then concentration drops to 15%. What is the original volume in the cask.

a. 30 litres

b. 36 litres

c. 40 litres

d. 54 litres

**2.**From a solution containing milk and water in the ratio 3 : 4, 10 L is removed and replaced by water. If the resultant solution contains milk and water in the ratio 1 : 2 then what was the amount of the original solution ?

a. 3 : 5

b. 4 : 7

c. 5 : 7

d. 3 : 2

**3.**10% of a solution of milk and water is removed and then replaced with the same amount of water. If the resulting ratio of milk and water is 2 : 3, find the ratio of milk and water in the original solution.

a. 4 : 9

b. 4 : 5

c. 5 : 4

d. 9 : 4

**4.**A beaker had 20 L of alcohol-glycerol mixture in the ratio 4 : 1 by volume. In the first round, 4 L of the mixture is removed and replaced with glycerol. In the second round, 5 L of the resultant solution is removed and replaced with glycerol. Finally, 10 L of the resultant mixture is removed and replaced with glycerol. What is the final quantity of glycerol in the mixture.

a. 15%

b. 18%

c. 24%

d. 76%

**5.**In a mixture of 80 L, milk and water are in the ratio 7:3. If 24 L of this mixture is replaced by 16 L if milk, find the final ratio of milk and water.

a. 10 : 7

b. 12 : 7

c. 23 : 7

d. 18 : 7