Question

I want to play a trick on my friend and hand him a big enough bunch of helium balloons to lift him into the air. Each empty balloon and the attached string weighs 0.02 pounds. Each balloon when inflated has the volume of a 2 ft diameter sphere. The helium in the inflated balloons is at approximately the same pressure as the air outside the balloon (standard atmosphere). How many balloons will lift my 145 lb friend?

Answer 1