LetA={ k, k1,..., 1, 0, 1,..., k1, k}where k is a positive integer.

1. Write all the elements of A when k = 3.
2. Find the mean of the set A when k=3, and then find the mean of A when k is not known.
3. Explain why, in general, A has 2k + 1 elements.
4. Using the results in parts b and c, find the standard deviation of A. Since k is not known, your answer will involve k.