Let the barrel contain 4 litres
of mixture.
$\therefore$ Wine = 3 litres
Water = 1 litre
Let x litre mixture is taken out.
$\therefore$ Wine in (4 – x) litres mixture = $\frac{3}{4}(4-x)$
On adding x litres water, water in
mixture, $(4-x)\times\frac{1}{4}$+4 ,
$\therefore$ x=$\frac{4}{3}$
Required answer = $\frac{\frac{4}{3}}{4}$ = $\frac{1}{3}$