Can You Solve The Two Rope Puzzle?
You have two ropes and a lighter. Each rope burns in 60 minutes, but the ropes do not burn at a constant rate. How can you measure 45 minutes by burning the ropes? Some of you might have heard this problem before. If so, try this variation: how can you measure 50 minutes? Watch the video for a solution to each problem.
Blog (formal math proof using sequences): http://mindyourdecisions.com/blog/2016/05/08/can-you-solve-the-two-rope-puzzle-classic-problem-and-variation/