Inventing Human Flight

I just finished a physics problem that I thought I would share with the blogger world:

In order to lift a 200 lb. man with a single helium balloon off the ground, the diameter of the balloon would have to be 5.4 m!

So to put worrying mothers at ease, NO, your child will not fly away if you leave him/her alone at an amusement park with too many balloons.

Check out this guy who set a record for highest flight with ordinary helium balloons getting to a height of 11,000 feet before the balloons started popping like a machine gun going off, and parachuting back down:
http://www.wired.com/culture/lifestyle/news/2001/10/47965

Or this other guy: who flys in his lawn chair with helium balloons and a BB gun to pop the balloons to bring him safely over the Oregon border. Unfortunately, we'll have to get costs down before we can make this an effective air travel option to get to work everyday:
http://www.huffingtonpost.com/2008/07/05/kent-couch-tries-flying-l_n_110980.html