?? 45 minutes exactly ?? hey guys, Will try explain this as best I can, sorry if it is not clear. Your aim Is to measure 45 minutes exactly. You have two ropes, which burn for 1 hour exactly each, however the rate at which they burn is not constant so you can't simply measure 3/4 of the length and burn to that point. Obviously you can light the ropes to start them burning. Good luck! -Spoon P.s u don't have a separate clock, watch or other way of measuring time!!