Question

A 90 liters container is filled with alcohol. If 3 litres of alcohol is replaced by water and this process is repeated one more time, find the quantity of alcohol left in the final mixture.

1. 84 litres
2. 84.1 litres
3. 84.2 litres
4. 84.3 litres
5. 84.4 litres

Answer 1

Correct Answer - Option 2 : 84.1 litres

Given:

The initial quantity of alcohol in the container = 90 litres

Quantity of water added each time = 3 litres

Formula used:

Alcohol left in container = [1 – (N/Q)]^T × Q

Where N = Quantity Removed

Q = Initial total quantity

T = Times of repetition

Calculation:

The final quantity of Alcohol in the container = [1 – (N/Q)]^T × Q

⇒ [1 – (3/90)]² × 90 litres

⇒ [(90 – 3)/90]² × 90 litres

⇒ (87/90)² × 90 litres

⇒ 84.1 litres

∴ 84.1 litres of alcohol left in the final mixture.