Michelangelo is being chased by a couple of cannibals who will kill him as soon as they get a hold of him. The only way to get rid of them is crossing the river bridge made of ropes and cut it on reaching the other end. He have found two diamonds in the woods each weighing 8 lbs. The rope is weak and can only accommodate a weight of 150 lbs. He weighs 140 lbs. Still he manages to cross the bridge and get rid of the cannibals with the diamonds without taking off any kind of clothing.
You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.
Light both the ends of the first string and one end of the second string. 30 minutes will have passed when the first string is fully burned, which means 30 minutes have burned off the second string. Light the end of the second string and when it is fully burned, 45 minutes will have passed.