If  10lt solution of water and alcohol containing 10% alcohol is to be made 20% alcohol solution, find the volume of alcohol to be added.
a. 1 lt                            b. 1.25 lt                      c. 1.5 lt             d. 2 lt


In 10 lt, alcohol is 10% = 1 lt.
Let x lt alcohol is added.
So, (1+x)/(10+x) = 20% = 1/5  =>  x = 1.25 lt.