How do you calculate 45 min without any clock and sense of time?

Question

There is two non uniform,unequal ropes. Every thing like weight,length etc are not same. But one thing is same. Each one is burned down within 1 hour. I'm giving you these two ropes and a candle just for the fire. So tell me How do you calculate 45 min without any clock and sense of time?

Google search for "burn ropes one hour" produces many discussions of the solution. — MJD, Jan 27 '15 at 02:14

score 3 · Accepted Answer · answered Jan 27 '15 at 02:30

First burn 2 ends of 1 rope, and 1 end of the second. That way it will last 30 minutes. As soon as the 1st rope burns out, set fire to the second end of the second rope. The second rope should burn in 15 more minutes instead of 30. Therefore 15+30=45, and you have just timed 45 minutes.

How do you calculate 45 min without any clock and sense of time?

1 Answers1