[Guest]

You have two 12" flammable ropes, a lighter, a knife. Each rope takes 1 hour to burn through when lighted on an end. Unfortunately, the rope burns unevenly and there is no way to know how fast any given section of the rope may burn. For example, the first 11" of the rope may burn in one minute while the remaining 1" smolders for 59 minutes.

How would you time 45 minutes using only burning rope?

Edited January 23, 2009 by SteveK

[Guest]

You have two 12" flammable ropes, a lighter, a knife. Each rope takes 1 hour to burn through when lighted on an end. Unfortunately, the rope burns unevenly and there is no way to know how fast any given section of the rope may burn. For example, the first 11" of the rope may burn in one minute while the remaining 1" smolders for 59 minutes.

How would you time 45 minutes using only burning rope?

Cut rope in half length-ways (each half should be half an hour). Now cut one of these in half lengthways (it will be 15 mins) now burn one half and one quarter to give you 45 mins

- Mel B

[bonanova]

Hi SteveK and welcome to the Den.

If you haven't already done so, please read the "read before posting" section,

especially about looking for puzzles that may already have been posted.

Yours is here, and discussion can be appended to that thread.

A related puzzle can be found here.

- bonanova

site moderator