Chapter 9, Problem 42EAP

Adding Up Asteroids. It's estimated that there are a million asteroids 1 kilometer across or larger. If a million asteroids 1 kilometer across were all combined into one object, how big would it be? How many 1-kilometer asteroids would it take to make an object as large as Earth? (Hint: You can assume they're spherical. The expression for the volume of a sphere is $\frac{4}{3}\pi r^3$ , where r is the radius.}