# Mr. X

• Mar 30th 2005, 11:01 AM
Brainiac
Mr. X
one person, lets call him Mr. X, walked south one mile, west one mile, and then back north one mile. he then looked around and noticed he was back where he started. where on the earth is this possible?

(note there is a really obvious answer honestly everyone gets in like 2 minutes, and because its so easy, ill just say it. if you havent figured out the answer when you are reading this, you definetly didnt think about the question. so, easy answer is: mr fubini was on the north pole. if you look at the intersections of the meridians, its kind of obvious.

however, there is another solution to the problem (this is the harder part).

if he wasnt on the north pole, then where was he?
• Mar 30th 2005, 02:20 PM
MathMan
I'm working on the equation...but...(Answer in white font, highlight to read)What about if your starting point was at a distance away from the pole where the circumference of the earth was one mile. The north and south movements cancel each other out and the west one mile would put you exactly were you started.
• Mar 30th 2005, 02:22 PM
MathMan
Answer in white font, highlight to readBecause 1/2, 1/3, 1/4, 1/5, miles away would also work; As long as you are located on a circle:

1 + 1/(2pi*n)

The west movement would be nullified as well. Assuming n is a positive integer.
• Mar 30th 2005, 03:13 PM
Brainiac
exactly right! nice thinking
• Aug 16th 2005, 08:18 PM
TheFarmer42
If the circumference is one mile, how is it possible to walk south one mile?
The maximum length you could walk in a southerly direction is 1/2 a mile.

On a pedantic note, i don't think it is a solution to reduce the earth's circumference - you need a more generic question - eg "a planet".

Update:
Ok, i was wrong. Someone should have picked that up by now!

Bonus points for working out how far north of the south pole the fella started walking (assuming he only went round once)...