Hi,
I was given this problem by my teacher and am curious to know how many science enthusiasts of you can solve it.
It took me quite a while. Take a look:
There are two lengths of rope.
Each one can burn in exactly one hour.
They are not necessarily of the same length or width as each other.
They also are not of uniform width (may be wider in middle than on the end), thus burning half of the rope is not necessarily 1/2 hour.
By burning the ropes, how do you measure exactly 45 minutes worth of time?
You can see the answer here:
http://mindcipher.com/puzzle/41-burning-rope
Enjoy!