Calculating 25 minutes by burning 2 inconsistently burning 1-hour ropes
You are given two ropes and are told that they burn at inconsistent rates, but will always take 1 hour to completely burn up. This means that cutting one of the ropes perfectly in half will not give you two smaller 30-minute ropes.
You are told that you need to approximately calculate 25 minutes by burning these ropes in some fashion.
How do you accomplish this?
Hint:
first ½ of hint
I carefully chose approximately instead of precisely
second ½ of hint
because to calculate it precisely would require that you ignite an infinite number of flames
Burn the four portions cut this way from the ropes, starting to burn them simultaneously. The 5/12 should be taken starting from the end of the ropes. When the second of these four pieces has burnt fully, say it’s approx 25 min.