[Guest]

A woman puts up a flyer offering to pay a lot of $ for a fence to be built around her yard. The less materials used, the better.

Three people go to offer ideas.

First, a construction worker goes to her and offers to put a stainless steel fence around her yard and lace it with barbed wire.

Second, an engineer goes and proposes a very complex plan that will use a lot of electricity but will shock any intruders trying to enter her house.

Third, a mathematician goes up to the lady. The mathematician is very excited about efficiency. How can the mathematician make sure that he is by far the cheapest bargainer while still meeting all of the requirements?

It is a little bit of a trick question - think outside the box.

He goes across the street and builds a fence around himself and declares the he is standing outside of the fence.

[Guest]

Didn't she say

that it had to be built around her yard?

[Guest]

Didn't she say

that it had to be built around her yard?

that's exactly what I was wondering...

[Guest]

Unless she owns everything besides the square he's standing in, that solution does not work under her requirements - keep people out of her yard.

Possible alternatives:

He builds the fence in only two dimensions, with a negligible 3D cost.

He installs an underground dog fence, with dog to attack intruders (which is apparently an unstated requirement for the fence), though what that has to do with him being a mathematician, I don't know.

He buys her yard so needs no fence, and so materials cost nothing.

He promises to take whichever of the other guys' plan is cheapest, buy a small fraction of the materials the other guy would use, and employ the axiom of choice (or similar idea) to make more at no cost.

He draws a Cartesian coordinate grid on the yard, with the origin in the center. Adding up the materials in each quadrant (because some become negative) ends with either a total cost of $0 or 0 total materials needed, depending on how you do the math.

Edited April 11, 2011 by pengwen

[Guest]

Either way she must be displeased

[Guest]

A woman puts up a flyer offering to pay a lot of $ for a fence to be built around her yard.

He goes to her property and marks off a square yard and builds a fence around that

[Quag]

Just build the fence the hight of i slat only of the fence ie/2- 4 inches. uses olmost no material but can be built around the whole yard. no where does it say how high fence must be.

[Guest]

Nowhere in the riddle does it give any specifications as to what the fence should be able to accomplish. Neither can you make the argument that 'a fence should keep out intruders,' as a visit to your local home improvement store could convince you that it is entirely possible for a fence to be purely ornamental. Personally, if we're looking for economy in resources I'd use twine and sticks I found on the ground. I would be well within the bounds of the original wording of the riddle.

[Guest]

well the solution is in a technicality, the mathematician built a fence "around her yard" with the word "around" being used by the definition of "being nearby" thus staying the qualifications she set in place