A freight car is a cuboid, its length is 4m, width is 1.5m, height is 4m, full of a car of sand, after unloading the sand piled into a 5 decimeter high cone How many square meters is the bottom area of the conical sand pile

A freight car is a cuboid, its length is 4m, width is 1.5m, height is 4m, full of a car of sand, after unloading the sand piled into a 5 decimeter high cone How many square meters is the bottom area of the conical sand pile

5 decimeter = 0.5 meter
Sand pile volume = 4 × 1.5 × 4 = 24 (M3)
Cone bottom area = 24 × 3 △ 0.5 = 144 (M2)

A conical sand pile has a bottom radius of 3M. If the weight of sand per square meter is 1.5 tons, how many tons does the pile of sand weigh?

π R * r * H / 3 * 1.5 (ton)
=π * 3 * 3 * 2 / 3 * 1.5 (ton)
=9 π (ton)

There is a cuboid water tank, which is 1.2m long, 0.8m wide and 0.4m high. The water surface of the tank is 30m high. Put a piece of iron with a length of 0.6m and a width of 0.5. The water is just full. Calculate the height of the iron

The title should be that the water surface of the tank is 3cm high, then 30cm = 0.3m
Iron block height 1.2x0.8x (0.4-0.3) / (0.6x0.5) = 0.32m