MHB Find the probability that each group has an equal amount of odd and even numbers

[Mehrudin]

A set of numbers 1,2,...,4N gets randomly divided into two groups with equal amount of numbers. Calculate the probability:7
a) Each group has an equal amount of odd and even numbers,
b) All numbers that are divisible by N, to fall in only one of the groups,
c) All numbers that are divisible by N, to be divided equally in the two groups.

 

[Greg]

It's unclear, at least to me, what the sequence noted as 1, 2, ..., 4N is. You need to give a better description. What is intended?