Most probably not. But it should be close to the population mean if various conditions are met:For example, the population should consist of independent, [nearly] identically distributed variables,...
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,...
Rude, not polite and kind of nasty. It is can also refer to someone who is not generous or is tight with their money. Try looking the word up in a dictionary.