Correct Answer - Option 3 : 120

**Given:**

The mixture is of 120 liters

Alcohol ∶ Water = 2 ∶ 1

**Calculation:**

Let initial quantity of alcohol and water be 2x and 1x.

⇒ 2x + 1x = 120

⇒ 3x = 120

⇒ x = 40

Initial quantity of alcohol = 2x

⇒ 80 litres

Initial quantity of water = 1x

⇒ 40 litres

Let the water to be added be x litres.

80/(40 + x) = 2/3

⇒ 240 = 80 + 2x

⇒ x = 80

Quantity of water in the newly made mixture = 40 + 80 = 120

**∴**** Required answer is 120 liters**