Total capacity = 50 x 32 x 20 = 32000 cm cube
3/4 filled = 3/4 x 32000 = 24000 cm cube
water : sand : total
5 : 1 : 5 + 1
5: 1 : 6
[24000 ÷ 6 = 4 000]
water : sand : total
5 x 4000 : 1 x 4000 : 6 x 4000
20 000 : 4000 : 24 000
20 000 cm cube = 20 000 ml = 20 litres
Ans: 20 litres of water