Numberphile rocks!! This is what math was made for! So, to break it down, if there are 3 toilets to select from, you have a 50% chance of selecting the most hygienic. If there are 4 toilets, your percentage drops to 46%. However, when N increases (meaning the number of toilets to select from increases), the likelihood that you’ll pick the cleanest one drops significantly to the point where it really doesn’t matter! Ha! Good luck! For the extended explanation, click here!