There are two separate usages of the term "worldly."
1) Pertaining to the physical world rather than the spiritual (e.g. worldly goods). 2) Sophisticated, knowledgeable about society and cultures (e.g. a worldly traveler)
The mean distance is the same as the mean of a set of numbers,but this time, instead of them just being numbers, they're lengths. You just simply add up all the numbers and divide the total length,...