125 gallons of a mixture contains 20% water. What amount of additional water should be added such that the water content is raised to 25%?

A 15/2 gallons

B 17/2 gallons

C 19/2 gallons

D 81/3 gallons

Correct Answer: Option D

Let, x gallons water should be added.

Here, 125 gallons of a mixture contains 20% water is (125× 20/100)= 25 gallons

According to the question,

25+x = (125+x)×25/100

=> 25+x = (125+x)×1/4

=> 4(25+x) = 125+x

=> 100+4x = 125+x

=> 4x-x=125-100

=> 3x=24

=> x=24/3

So, x=81/3

So, 81/3 gallons water should be added. (Ans.)