Let initially there be 7 litres of mixture.
Amount of water = 2 litres
Amount of alcohol = 5 litres Let x litres of mixture be rep laced with water.
Quantity of water in 7 litres of mixture = 2 litres
Therefore,
Quantity of water in x litres of mixture =
litres
Quantity of alcohol in 7 litres of mixture = 5 litres
Therefore,
Quantity of alcohol in x litres of mixture =
litres
Quantity of water in new mixture is
⇒
(2−+x) Quantity of alcohol in new mixture is
⇒
(5−) According to the question, the new mixture contains water and alcohol in equal parts,
= 1
5− = 2 +
3 =
x = 2.1 litres
Hence, it is the required result.