∵ Volume of cuboid = Length × Breadth × Height When the length and breadth of a cuboid are constant, then volume of cuboid ∝ height of cuboid Let volume of cuboidal tank be xh, Where h is the height of the tank and ‘x’ is the product of its length and breadth When height of water = 3.5 cm, volume of water = 94.5 litres = 94500 cm3 [∵ 1 litre = 1000 cm3 ] ⇒ x = 94500/3.5 = 27000 cm2 Now, when the tank is 64% filled height of water = 32 cm, ⇒ 64% of Height of tank = 32 cm ⇒ Height of tank = h = 32/0.64 = 50 cm ∴ Full capacity of tank = xh = 27000 × 50 = 1350000 cm3 = 1350 litres Alternate method When height of water is 3.5 cm then water volume = 94.5 lt Now, when height of water is 32 cm then water volume = 94.5 × (32/3.5) = 864 lt According to question, 64% of capacity of tank = 864lt ∴ 100% capacity of tank = 864 × (100/64) = 1350 lt.