A spherical balloon weighs 120 lb including the "basket" but not including the gas when inflated. When

inflated with helium (specific weight 0.016 lb/ft³) the balloon has a radius of 10 ft. How much cargo can

the balloon carry if it is in air with a specific weight of 0.075 lb/ft³?

Hint: The balloon buoyant force is equal to the weight of the fluid (air) displaced. You will need to

determine the total weight of the balloon including the helium lighter. Recall that the volume of a sphere is

(4/3)*T*r³