Two points within the Arctic Circle are chosen at random, using a uniform distribution over the entire area. That is, any region of a given area is as likely as any other region with that area, to receive a given point.

What is the expected value of their great circle distance from each other?

Assume:

• The Earth is a perfect sphere with radius 3,958.8 miles.
• The Arctic Circle is located at 66.55° North.

Both calculus answers and simulation answers are welcome. As we are using approximations here, especially about the perfect sphericity of the Earth, the exactness of calculus is not really needed.

Part 2:

... and how about two points on the whole Earth?

(In reply to re: soln by Steve Herman)

The difference is due to the puzzle's use of the average radius of the Earth, rather than one corresponding to a quadrant of a 360 degree double meridian. 

Posted by Charlie on 2022-10-21 19:01:21