Four people are on the end of a bridge and they all walk at different rates. One takes 1 minute to cross, one take 2 minutes, one takes 5 minutes, and the last takes 10. It is super dark out and there is only 1 flashlight. The flashlight is bright enough that 2 people can cross at once with it. The flashlight battery will die in 17 minutes. No one can go anywhere without a flashlight. How can they all get across before the flashlight dies? Can you solve it? Come to this seminar and have your mind blown by this puzzle and other ones.