The volume for a pyramid is [tex]V= \frac{1}{3} Bh[/tex] where B is the area of the base and h is height. We are given the volume and the dimensions of the base and just need to find the height. [tex]V= \frac{1}{3} (25*18)h[/tex]. Simplifying a bit on the right we have 525 = 150h. Dividing both sides by 150 gives us a height of 3.5