The Following Table Lists the Width of the Great Pyramid

Short Answer

The following table lists the width of the Great Pyramid of Egypt at different heights.The Pyramid has a square base and each layer is a square.
$$\begin{array} { r c c c c c } \text { height (ft) } & 0 & 100 & 200 & 300 & 400 \\\text { side length (ft) } & 750 & 562 & 375 & 189 & 0\end{array}$$ Find a good estimate (in ft³)for the volume of the Great Pyramid.