Given two identical wires each of which can burn completely in 1 hour. You need to tell a way to measure 45 minutes using these wires.
Note: The wires burns non-uniformly. It doesn’t mean that half of the wire will burn exactly in 30 mins.
Lit the first wire from the both ends and second wire from one end. The first wire will completely burnt out in 30 mins. Now lit the second wire from the other end. As 30 mins have been already passed the second wire will need more 30 mins to burnt down completely but if we light the second end it will burnt out in 30/2 = 15 mins.
30 mins + 15 mins = 45 mins