Question

A bottle contains 20 litres of liquid A., 4 litrs of liquid A is taken out of it and replaced by same quantity of liquid B. Again 4 litres of the mixture is taken out and replaced by same quantity of liquid B. What is the ratio of quantity of liquid A to that of liquid B in the final mixture?

(a) 4:1

(b) 5:1

(c) 16:9

(d) 17:8

Answer 1

Correct option is (c) 16:9

A bottle contains 20 litres of liquid A.

After removing 4 L of liquid A and adding 4 L of liquid B.

Mixture become this way.

16 L of A and 4 L of B

⇒ A = 16/20 and B = 4/20

Now again 4 L of mixture is taken out and 4 L of liquid B is added.

⇒ A : B = [16 – (16/20 × 4)] : [4 – (4/20 × 4) + 4]

⇒ A : B =  16× [1 – (1/5)] : 4 × [2 – (1/5)]

⇒ A : B = 16 × 4/5 : 4 × 9/5

⇒ A : B = 16 : 9

∴ The ratio of quantity of liquid A to that of liquid B in the final mixture is 16 : 9.