25 litres of a mixture contains 30% of spirit and rest water. If 5 litres of water be mixed in it, the percentage of spirit in the new mixture is :

25%

Quantity of mixture = 25 L,

 Spirit : Water

   3     :    7

⇒ (3 + 7)x = 25 L

⇒ 10x = 25 L

⇒ x = 2.5

⇒ Spirit = 3 x 2.5 = 7.5 L

⇒ Water = 7 x 2.5 = 17.5 L

Adding 5 L water in the solution,

⇒ 17.5 + 5 = 22.5 L

⇒ Percentage of Spirit in the new solution = \(\frac{7.5}{22.5 + 7.5}\) x 100 = \(\frac{7.5}{30}\) x 100 = 25%.