GMAT Quantitative Reasoning Practice Test 3

First calculate the volume of water that has been poured into the tank. If it has been poured at a rate of 8 cubic feet per minute for $2.5$ minutes, $8\times 2.5=20$ cubic feet. The tank is rectangular, so its volume is length × width × height (or depth),
with the answer in cubic units. We are given the length, and can calculate the width, since we are told that the width is 1/2 the length, or 1/2 of 3 feet, or 1.5 feet. The volume we have already calculated to be 20 cubic feet. Therefore, 20 = length × width × height, or $20=3\mathrm{feet}\times 1.5\mathrm{feet}\times \mathrm{the}\mathrm{height}.$ Solving for the height, we get 40/9, or approximately $4.44$ feet.