(4/3)pi*r^3 (formula for the volume of a sphere)

= (4/3)pi*(2160/2 mi)^3

= (pi/6)*(2.16*10^3 mi)^3

= (pi/6)*10.077696*10^9 mi^3

= (4/3)pi*(2160/2 mi)^3

= (pi/6)*(2.16*10^3 mi)^3

= (pi/6)*10.077696*10^9 mi^3

**≈ 5.28*10^9 mi^3**(3 significant figures, as is the diameter data)