A heap of sand is in the shape of a right circular cone whose base diameter is 24 m and whose height is 7 m. What is the volume of sand in the heap, in cubic metres? (Use π = 22/7.)

The radius is 24/2 = 12 m. Volume = (1/3)π$r^{2}h=(1/3)\times (22/7)\times 144\times 7=(1/3)\times 3168=1056$ cubic m. The trap 3168 is that same figure with the 1/3 dropped, which is the volume of a CYLINDER on the same base and height; 4224 uses the diameter 24 m as the radius; 352 divides by 3 a second time.