Logic Problem

[Dan]

Here's a thinking problem:
You have a pack of matches and two lengths of wick (both are different lengths) that you know will take exactly 1 hour to burn if you light their end on fire. The thickness of the wicks changes along their length, and their materials changes (the speed of burn isn't constant), so cutting a wick in half will not give you two wicks that will burn in half an hour.

How can you measure out 45 minutes?

I promise it's not a trick question or anything.

 

[LiquidToast]

with a watch ^_^

 

[Shamrock]

with a watch ^_^

Ding, ding, ding.

 

[Dan]

you have a pack of matches and two wicks that's it

 

[the_lone_wolf]

burn one wick to measure an hour, then see how many matches you can burn in that hour, then simply burn three quarters of that number of matches to measure 45 minutes

pwnt

 

[Nat Turner]

Here's a thinking problem:
You have a pack of matches and two lengths of wick (both are different lengths) that you know will take exactly 1 hour to burn if you light their end on fire. The thickness of the wicks changes along their length, and their materials changes (the speed of burn isn't constant), so cutting a wick in half will not give you two wicks that will burn in half an hour.

How can you measure out 45 minutes?

I promise it's not a trick question or anything.

A) Light both ends of the first wick, and one end of the second wick. (make sure the two wicks are NOT connected)

B) Wait until the first wick burns out

C) Light the second end of the second wick

Wait until that burns out, and it's 45 mins.

I just figured that out yay.

 

[Dan]

nat's got the answer. Lone Wolf's solution would be good too(assuming you've got almost two hours worth of matches which is a bit much for one pack)

 

[short recoil]

It's gotta be something about burning off 15 minutes of one fuse timing it using the other, but i can't figure out a way to time 1/4 of one of them burning, without a watch because you can't measure the length nor time without a watch, being different you cannot compare the 2.
Nat's got a way of finding 45 mins but there is no way of measuring out 45 mins of fuse without burning it?

 

[Nat Turner]

nat's got the answer. Lone Wolf's solution would be good too(assuming you've got almost two hours worth of matches which is a bit much for one pack)

This was a really cool problem.

 

[the_lone_wolf]

nat's got the answer. Lone Wolf's solution would be good too(assuming you've got almost two hours worth of matches which is a bit much for one pack)

don't know about you but i buy big packs of matches, and i would have a wick left over, they sound pretty pricy those winks and i'd have a reference to use in the future too:thumbs:

 

[Lou]

A) Light both ends of the first wick, and one end of the second wick. (make sure the two wicks are NOT connected)

B) Wait until the first wick burns out

C) Light the second end of the second wick

Wait until that burns out, and it's 45 mins.

I just figured that out yay.

makes sense... with the first wick you measure 30 minutes... at which point you will have 30 minutes left of the second wick.. you burn the other end and that reduces the time left on that wick to 15 minutes. very clever =) How would you measure 47 minutes?