Fuses: Difference between revisions
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You have two fuses, each twelve inches long. Each fuse burns in exactly one hour, but does not necessarily burn at a uniform rate. Also, the two fuses do not necessarily burn at the same rate over corresponding segments, but a given segment on a given fuse burns in the same amount of time in either direction. How do you use these two fuses to time 15 | You have two fuses, each twelve inches long. Each fuse burns in exactly one hour, but does not necessarily burn at a uniform rate. Also, the two fuses do not necessarily burn at the same rate over corresponding segments, but a given segment on a given fuse burns in the same amount of time in either direction. How do you use these two fuses to time 15 | ||
minutes? (You are allowed as much time to prepare as you wish.) | minutes? (You are allowed as much time to prepare as you wish.) | ||
{{Solution| Take one fuse and bend it so that it forms a loop. Call this fuse $f_1$}} | |||
==Extension== | ==Extension== | ||
Revision as of 18:43, 6 November 2010
A very nice puzzle from Problem Solving by Thomas DeFranco and Charles Vinsonhaler.
Puzzle
You have two fuses, each twelve inches long. Each fuse burns in exactly one hour, but does not necessarily burn at a uniform rate. Also, the two fuses do not necessarily burn at the same rate over corresponding segments, but a given segment on a given fuse burns in the same amount of time in either direction. How do you use these two fuses to time 15 minutes? (You are allowed as much time to prepare as you wish.)
Solution
Take one fuse and bend it so that it forms a loop. Call this fuse $f_1$
Extension
How do you time 15 minutes using only one fuse?
References
Problem Solving by Thomas DeFranco and Charles Vinsonhaler.