A cuboid iron block with a length of 8cm, a width of 7cm and a height of 6cm and a cube iron block with an edge length of 5cm are melted into a cylinder with a diameter of 20cm. What is the height of the cylinder? (accurate to 0.01cm)

Let the height of the cylinder be xcm, 8 × 7 × 6 + 53 = π × (20 △ 2) 2x, and the solution is x ≈ 1.47 A: the height of the cylinder is 1.47cm

Cylinder oil tank, horizontal, 5.24m long, 2.7m diameter, remaining oil 0.4m high, what is the volume? How to find, please give the detailed formula
Calculate the volume when the remaining oil height is 0.4m

How is the data inconvenient to calculate? Is there a mistake?
According to the Pythagorean theorem, the oil surface length w = (R ^ 2 - (R-H) ^ 2) ^ (1 / 2) * 2
According to the triangle area calculation formula, the triangle area S1 of oil side section is = (R-H) * (R ^ 2 - (R-H) ^ 2) ^ (1 / 2)
According to trigonometric function, the angle between oil surface and center line α = 2arccos ((R-H) / R)
The corresponding sector area S2 = 1 / 2 * π * r * r * α / π = α * r * r / 2 is obtained from the sector area calculation formula
The oil storage is equal to its side cross-sectional area * length, so the oil storage v = (s2-s1) * L
It is suggested that the input data should be calculated by computer
If you find the remaining stock, you subtract V from the total volume

Cylinder diameter 1.6m, height 2.5m, volume

Radius square × π × height = volume
0.8 × 0.8 × 3.14 × 2.5 = 5.024 M3

A cuboid iron block with a length of 8cm, a width of 7cm and a height of 6cm and a cube iron block with an edge length of 5cm are melted into a cylinder with a diameter of 20cm. What is the height of the cylinder? (accurate to 0.01cm)