The mass of Saturn's rings is 2x1019 kg. What is the ratio o...

Prompt

The mass of Saturn's rings is 2x1019 kg. What is the ratio of this mass to that of a 200 km diameter spherical moon made entirely of water-ice (density ~ 1 g/cm3)? That is what is Mrings : Micy moon? A) 1 : 1 B) 50 : 1 C) 5 : 1 D) 0.5 : 1