An aquarium has a length of 20 inches, a width of 10 inches, and a height of 18 inches. The directions tell you to fill the aquarium until you have a 2-inch gap between the top of the water level and the top of the aquarium. What is the volume of the water?

400 in. 3

3,600 in. 3

3,200 in. 3

2,304 in. 3

The answer is 3,200 in. 3

The volume of the rectangle (V) with length l, width w, and height h is:

V = l * w * h

If you want to fill the aquarium until you have a 2-inch gap between the top of the water level and the top of the aquarium, then the height of the water space is 2 inches smaller than the height of the aquarium. Therefore:

l = 20 in

w = 10 in

h = 18 in - 2 in = 16 in

The volume of the water is:

V = 20 * 10 * 16 = 3,200 in ³