Find the volume of a rectangular parallelepiped that is 21 cm long and 3/7 of the length and 30 percent of the height.

Let’s write the formula for the volume of a parallelepiped:
volume = length x width x height.
Only length = 21 cm is given.But we will find the remaining dimensions by the condition:
width = 3/7 length = 3/7 * 21 (cm) = 9 (cm) = 30% of height = 0.3 * height;
height = width: (0.3) = 9: (0.3) = 30 (cm).
Now you can find the volume of the parallelepiped:
Volume = 21 cm * 9 cm * 30 cm = 5670 cm ^ 3 = 0.00567 m ^ 3.