You have two cloth ropes. The ropes have non-uniform thicknesses and are of different lengths. You also have a bucket of colored liquid. When you dip an end of a rope into the liquid, the colored liquid wicks through the rope, progressing through it at some non-constant rate. The total wick-time for the ropes is 1 hour each. How would you measure 45 minutes using only the ropes and the liquid ?