Helium Balloon Question....Help!! A 600 kg weather balloon is designed to lift a 4000 kg package. What volume should the balloon have after being inflated with helium at standard temperature and pressure in order that the total load can be lifted? density of helium .179 and air is 1.29. I have tried looking at problems that are similar and I set it up like this: weight total = weight package + weight balloon + weight of helium weight total = Fb = (density of air - density of helium) V g However i dont know how to find the weight of the helium? Help greatly appreciated!!