Correct Answer - Option 2 : 54%
Given:
⇒ Quantity of chemical in mixture = 90 × 4/9 = 40 litres
⇒ Quantity of water in mixture = 90 - 40 = 50 litres
Let quantity of chemical and water added in to the mixture be a litres.
⇒ (40 + a)/(50 + a) = 11 : 13
⇒ 520 + 13a = 550 + 11a
⇒ a = 15
⇒ Quantity of water in new mixture = 50 + 15 = 65 litres
⇒ Total quantity of new mixture = 90 + 15 + 15 = 120 litres
∴ Required percentage = 65/120 × 100 = 54.166 ≈ 54%