One litre of water is added to 5 litres of alcohol-water solution having 40% alcohol strength. The strength of alcohol in the new solution will be:

$33\frac{1}{3}$%

Alcohol strength is 40% in alcohol water mixture .

So, Amonut of alcohol = \(\frac{40}{100}\) x 5  = 2 litre

Amount of water in mixture = 5 - 2 = 3 litre

Now, One litre of water is added to 5 litres of alcohol-water solution

New amount of water in mixture = 3 + 1 = 4 litre

Total amount of mixture = 5 + 1 = 6 litre

New strength of alcohol = \(\frac{2}{6}\) x 100

= 33\(\frac{1}{3}\)%