Physics
posted by mymi .
A 1.8g balloon is filled with helium gas. When a mass of 4.8 g is attached to the balloon, the combined mass hangs in static equilibrium in midair. Assuming that the balloon is spherical, what is its diameter? (The density of helium is 0.179 kg/m3, and the density of air is 1.3 kg/m3.)

These problems can be solved using Archimedes principle. Show your work foor additional assistance.