Given:

The ratio of sprit and water = 2 : 5

Formula used:

If the volume is increased by a%, then the new volume will be [(100 + a)/100] × initial volume

Calculation:

Let an amount of sprit and water be 2 x and 5 x respectively and also let y liter is added to sprit.

Total volume = 2 x + 5 x

⇒ Total volume = 7 x

After adding y liter, new volume = 7 x + y

According to the question, the new volume of a solution is increased by 50% after adding sprit only.

⇒ The new volume of a solution = [(100 + 50)/100] × 7 x

⇒ 7 x + y = [150/100] × 7 x

⇒ 7 x + y = 10.5 x 

⇒ 10.5 x – 7 x = y

⇒ 3.5 x = y

⇒ x/y = 1/3.5 

The resultant ratio of sprit and water = (2 x + y)/5 x

⇒ The resultant ratio of sprit and water = (2 x/5 x) + y/5 x

⇒ The resultant ratio of sprit and water = 2/5 + 3.5/5

⇒ The resultant ratio of sprit and water = (2 + 3.5)/5

⇒ The resultant ratio of sprit and water = 5.5/5

⇒ The resultant ratio of sprit and water = 11/10

∴ The resultant ratio of sprit and water is 11/10