How deep would the water be?

Question

The lake created by Hoover Dam on the Arizona-Nevada border has a capacity of 31,250,000 acre-feet. If the whole lake suddenly flooded the Mojave Desert (area 15,000 sq. miles) how deep would the water be? Assume the Mojave Desert is completely flat. (An acre-foot is the volume of water that would cover an area of 1 acre to a depth of 1 foot. An acre is 43,560 ft.)

Answer 1

You have the volume, and since you're given the area, you can divide the volume by the area of the base of this new shape to get the height (which is, in this case, the depth). However, you must first convert $15000$ square miles to square feet and $31250000$ acre-feet to cubic feet.

So, we do: \begin{align} \dfrac{31250000 \times 43560}{15000 \times 5280^2} \approx 3.255 \text{ feet deep} \end{align}