A lighter-than-air spherical balloon and its load of passengers and ballast are floating stationary above the earth. Ballast is weight (of negligible volume) that can be dropped overboard to make the balloon rise. the radius of this ballon is 4.67m. Assuming constant value of 1.29 kg/m^3 (density of air), determine how much weight must be dropped overboard to make the balloon rise 122m in 23 s.