There is a certain kind of rope which takes exactly one hour to burn from end to end. The rope is not uniform, not symmetric - thicknesses throughout its length vary randomly. No two such ropes will be identical.
You have two such ropes. How will you measure 45 minutes?
2007-03-09 20:10:18 · 5 answers · asked by mike 1 in Science & Mathematics ➔ Mathematics
light 1 rope on both ends. Light the second rope on one end. When the first rope finishes burning, 30 minutes will have passed (since you lit in on both ends)
immediately light the other end of the 2nd rope - it should have "30 minutes" of rope left, but since it is now burning on both ends, this should take 15 minutes.
Exactly 45 minutes have now passed. Problem solved
2007-03-09 20:16:21 · answer #1 · answered by Bill F 6 · 4⤊ 0⤋
with a provide up watch! or you ought to mild the two ropes at the same time, one burning the two ends and the different merely burning one end. After 30 mininutes the 1st could have thoroughly burnt out and the 2d could have a million/2 an hour left so which you mild the different end of that and it will take yet another 15 minutes for that to thoroughly burn subsequently measuring 40 5 minutes.
2016-12-14 15:22:00 · answer #2 · answered by Anonymous · 0⤊ 0⤋
note "It should have 30 mins of rope left" is only a guess, rather than a guarantee.
I like my answer: I will measure 45 minutes with my watch and use the rope to tie my laces.
2007-03-11 11:55:08 · answer #3 · answered by Tony W 2 · 0⤊ 1⤋
Genius. Totally agree with Bill F.
2007-03-11 05:06:26 · answer #4 · answered by Anonymous · 0⤊ 0⤋
very confusing thing. lookup using yahoo. that will may help!
2014-11-06 16:28:13 · answer #5 · answered by ? 3 · 0⤊ 0⤋