Correct Answer - Option 2 : 105 liters
Given:
The ratio of alcohol and water in a solution of 70 liters is 5 ∶ 2.
Concept used:
Ratio method
Calculation:
The ratio of alcohol and water in a solution of 70 litres is 5 : 2
Quantity of alcohol
⇒ 70 × (5/(2 + 5))
⇒ 50 litres
Quantity of water
⇒ 70 × (2/(2 + 5))
⇒ 20 litres
According to the question,
The ratio of alcohol and water in a solution 2 : 5
Alcohol quantity is same then,
⇒ 2 unit → 50 litres
⇒ 1 unit → 25 litres
Then, water is added
⇒ 5 unit → 5 × 25
⇒ 125 litres
Water should be added to the solution
⇒ 125 – 20
⇒ 105 litres
∴ Water should be added to the solution to reverse the ratio is 105 litres.
