You have these two strings of unequal lengths. They both take exactly one hour to burn from one end to the other when Lighted at any end. But they do not burn at a uniform rate; some sections Burning faster than others and some slower, in a random fashion, which Cannot be predetermined. Any point on either of the strings, However, burns at the same rate forward or backward, whichever end is Lighted. and a match-box. Without any other help, and without Cutting the strings, how would you determine exactly 45 minutes?