Count 45 minutes with 2 ropes that burn one hour each.

There are 2 ropes that are not of same lenght , but both take an hour each to burn completely.
You are given a lighter and no clock. You have to measure 45 minutes.

Answer: Light one rope from both ends and another rope from one end. The rope that is lit from both ends burns out completely in 30 minutes. The rope that is lit at one end is burnt half. At this point of time, light the other end of the rope too. The left half of the rope will burn in 15 minutes.