Question

A storage container is in the form of a frustum of a pyramid 4m square at the top and 2.5m square at the bottom. If the container is 3m deep, what is its capacity in m3

Answer 1

You can find many derivations of the formula. If the two bases have area S1 and S2, then the volume is
h/3 (S1 + S2 + √(S1*S2))
Now just plug in your numbers