Comments on: Brain Teaser: Making Ends Meet

By: paula

paula — Wed, 21 May 2008 18:24:41 +0000

i don’t think you can say just like that how many people will finish tying the ropes…asumpting that evryone manages to tie the first ends of the ropes and than the other two,we get 2 loops for evry person ..wich means 240 loops…i mean we can only say wich is the maximum number of loops that the 120 persons can create and not how many of them will manage to do what they’re asked

By: Ali

Ali — Sat, 17 May 2008 12:49:34 +0000

Correction, your solution is the right one since the answer is the same whichever of the 4 ends is selected first.

By: Ali

Ali — Sat, 17 May 2008 08:31:44 +0000

The answer given does not address the problem as initially set out, which was to start by taking a random selection of any two ends at which point you have a 50:50 chance of selecting ends from two different ropes and you end up with an average of 180 loops. The given answer only works if having already selected one of 4 available ends you are asked to tie that to one of the reamining 3.

By: J

Fri, 16 May 2008 00:02:52 +0000

I agree with both B and C’s replies; the question was both unclear and complicated. However, I did like figuring it out and came up with 120 loops, also.

By: CB

CB — Thu, 15 May 2008 11:38:37 +0000

I agree completely with C. I don’t see the logic in attempting to complicate a rather simple solution.

By: C

Mon, 12 May 2008 01:27:08 +0000

B is right. What is a loop for the author?
If I take two ropes and tie them one end to one end, I get a longer rope wit two ends free, Then I tie those two free ends and I get a big loop. Ecah person gets one big loop, which gives a total of 120 loops. What is wrong with this logic versus the formulation of the problem?

By: Sue

Sue — Thu, 01 May 2008 15:38:50 +0000

Yeah..yeah
Try this..2 loops for each knot tied and 1 loop that the ties create.

By: Govardhan

Govardhan — Wed, 30 Apr 2008 08:35:46 +0000

i dont agree with, what Wes is saying…This question can have multiple answers…

By: Paul

Paul — Fri, 11 Apr 2008 07:59:33 +0000

You can not base mathematical logic on a human condition – Assumption. You’re argument is valid, provided your assumption of the people will do, what you expect.

By: zenkat

zenkat — Fri, 04 Apr 2008 14:05:34 +0000

Fun little problem, but I have one minor quibble. Since the initial selection of an open or closed end is random, the answer is a statistical distribution, with 160 loops as the expected mean.

Bonus question: what is the standard deviation of the distribution?