Given: The quantity of mixture = 400 liters
The ratio of soda and alcohol = 4 : 1
100 liters fo mixture is taken out and replaced with 100 liters of alcohol
Calculation: Quantity of soda
=400×=320 litres
Quantity of alcohol
=400×=80 litres
⇒ Quantity of soda taken out
=100×=80 litres
⇒ Quantity of alcohol taken out
=100×=20 litres
⇒ Rest amount of soda in the vessel = 320 - 80 = 240 litres
⇒ Rest amount of alcohol in the vessel = 80 - 20 = 60 litres
⇒ New amount of alcohol in the vessel = (60 + 100) = 160 liters
Now, Required ratio = 240 : 160 = 3 : 2
∴ The required ratio of soda and alcohol in the mixture = 3 : 2.