Assume a pyramid, such that each of the triangle faces are equilateral triangle.
Let's call this pyramid p4.
Now, let's say there's a tetrahedron, which is also a pyramid but with the base being a equilateral triangle.
Let's call this p3.
The question is, what is the ratio of volume of p3 and p4?
(You are to solve this problem by insight, and you are not allowed to use algebraic formulas.)