Find the ratio of milk and water

Question

The ratio of milk to water in a container is 5 :1 by volume.If the total volume of mixture is 9 litres , find the volume of water in it......Plz solve this question

Answer 1

milk/water=5/1... 5+1=6... 9/6=1.5... milk=5*1.5=7.5... water=1.5, sum=9

Answer 2

milk : water 5 : 1, total ratio 5 + 1 = 6, total volume = 9, milk = total volume x milk ratio/total ratio, milk = 9 x 5/6, milk = 7.5, water volume = total volume - milk, water volume = 9 - 7.5, water volume = 1.5