I'm not sure where the 50% came from off the top of my head, but I think the 73% is wrong (should be 63%). My math: If there is a 1% chance of something happen

I'm not sure where the 50% came from off the top of my head, but I think the 73% is wrong (should be 63%). My math: If there is a 1% chance of something happening in a given sample, there is a 99% chance of it not happening. So, for a set of N samples, you multiply 0.99 * 0.99 * 0.99... N times or 0.99^N to determine the chances of it not happening in any of the samples. 0.99^100 is about 0.37. 1- 0.37 = 0.63.