I debated on putting this in the thread a couple down from this, but since they are two totally different questions, I figured this should be okay. After seeing this on the news today some of my co-workers were talking about if the balloon could even lift the child. They had seen an episode of Mythbusters on the subject and were curious. I tried to work it out, but there is where my question comes in. How does one figure out what it takes to lift, say, a 60lb object as high as the balloon was. I'm sure if they story said, but for numbers sake let's use 250 feet off the ground and the city is 5000 feet above sea level. I used volume of a cylinder since that's the closest shape formula I knew to what it looked like - a 20x5 cylinder. I looked up that there is 8.3 grams of lift per 8.2 liters of helium and went from there. But how do you figure out what volume of helium you'd need to lift this object 250 feet off the ground as I am sure it changes as you get higher.