2 litre of pure alcohol is  added to 6 litre, 40% alcohol solution. The percentage of water in the  solution is:

• 65%

• 45%

• 55%

• 60%

B.

45%

Amount of alcohol in 6 litres of solution

Amount of water in 6 litres of solution
 =6 - 2.4 = 3.6 litre

Now, the added amount of alcohol in 6 litres solution is 2 thus, amount of alcohol in 8 litres of solution = 2.4+2 = 4.4
Amount of water in 8 litres of solution = 3.6 litre
therefore, % of water in the solution = 
= 45%