Question

A container contains 80 liters mixture, in which there is 25% nitrogen. Find the quantity of pure nitrogen to be added in it to make the solution contain 40% nitrogen.

1. 18 litres
2. 15 litres
3. 20 litres
4. 12 litres

Answer 1

Correct Answer - Option 3 : 20 litres

Given:

Mixture =.80 litres

Percent of nitrogen in the container = 25%

Calculation:

Quantity of nitrogen = 80 × 25%

⇒ Quantity of nitrogen = 20 litres

Let the added quantity of nitrogen be x litre.

After adding x litre nitrogen,

Total quantity of nitrogen = x + 20

Total quantity of container = x + 80

According to the question,

⇒ {(x + 20)/(x + 80)} × 100 = 40

⇒ {(x + 20)/(x + 80)} = 40/100

⇒ 5x + 100 = 2x + 160

⇒ 3x = 60

⇒ x = 20 litres

∴ The added quantity of the nitrogen is 20 litres.