Correct Answer - Option 4 : 77 litres
Given:
Initial quantity of mixture = 55 litres
Initial ratio of mixture = 2 : 3
Final ratio of mixture = 1 : 5
Calculation:
Let initial quantity of alcohol and water be 2x and 3x.
⇒ 2x + 3x = 55
⇒ 5x = 55
⇒ x = 11
Initial quantity of alcohol = 2x
⇒ 22 litres
Initial quantity of water = 3x
⇒ 33 litres
Let the water to be added be x litres.
22/(33 + x) = 1/5
⇒ 110 = 33 + x
⇒ 77 = x
∴ Quantity of water added is 77 litres.