Please try this hard riddle

Question

While putting together some explosive devices during a deployment, an EOD specialist needs to measure exactly 15 minutes. His watch has been broken in combat and he only has a bunch of detonation cords. The only thing that he knows about them is that they burn up in exactly one hour, once they are lit one cord = one hour). The speed at which they burn however, is not constant. How can he determine a 15 minute period by only using these cords?

Answer 1

how can you say  that each chord burns in exactly one hour then say the speed at which they burn is not constant? that doesnt make sense to me? if the first statement is true and the chords burn in exactly one hour, i would fold one chord in half, cut it, light it at both ends, in which case you have 15 minutes when the flames meet in the middle? but if the second statement is true and the speed is never the same then i would have no idea.

Answer 2

well then he needs to start counting time in his head and tie knots in the cord for every minute he counts out. when he has 15 knots...he has fifteen minutes...

Answer 3

some 1/4 thinjgy he needs to do.

Answer 4

1001, 1002, 1003, 1004, 1005, and on and on..........

Answer 5

first. cut the cord in half. then. cut it in half again. then u burn it!

yay! did i get it! wooooooooooot!

shake shake shake! shake shake shake! shake ur booooooty! shake ur boooooty!  shake shake!  shake shake!  

Answer 6

All the people who are saying cut it and cut it again need to re read the riddle

"The speed at which they burn however, is not constant."

I've tried to figure it out but I can't...  

Answer 7

He shoudl light 1 cord at both ends and the second cord at one end.

When the first cord burns out, he should light the second cord at the other end.

The time between now and the second cord burning out completely is 15 mins

Answer 8

SPAM

Answer 9

Burn 1 cord completely, and measure with three sticks the angle of the sun for 1 hour! Now using the cords find the half hour angle, and then the 15 minute angle!

So now you can measure 45 minutes with the sun!

Burn all cords for the 45 minutes and all the lengths resting are 15 minutes!

Answer 10

DONT KNOW!! :D

If u dont get the right answer edit it bcoz i wanna know...

Answer 11

You get a Star quite interesting cause i can't figure it out.

Answer 12

cut one of the cords into fourths and wait til its done burning... voila!!! 15 minutes has gone by!!!

Answer 13

Let's see.....

He can take the cord, halve (fold the whole thing into a loop) it so that it's doubled, then halve the whole thing again. Now take one of the ends, which is now an exact fourth. Burn that.

And, if the cord will still work this way, take it, cut it down the middle. Take the cut half and middle-lengthwise-cut-it again. That, according to my younger sister would work.

But then, I'm no mathematician! For sure.

Answer 14

he cuts 3/4ths of the cords off

Answer 15

probably: use ¼ of cord – ¼ of hour = 15 min. --

- (add) proposed answer too simple? _ (and how is ‘not constant rate’ a factor?) –

reading Manisha’s message: complicated but ingenuous, & maybe correct.

- (edit)  Davght’s answer – if  tongue-in-cheek (or maybe I don’t get it?); – haha & all you left out is Rotation of the Earth & Rainfall factor – &

- tatted_  e.g  Ã¢Â€Â“ when think about it, the thing is: 1 hour TOTAL for burning, but burns faster-&-slower during that period. so in effect you can count the hour with it but not the minutes – so,

     stumped for now & will wait for Answer…

Answer 16

um...he can count the fifteen minutes DUH!