Find Each Value Requested for the Set of Scores in the Following

Short Answer

Find each value requested for the set of scores in the following frequency distribution table.
$$\begin{array} { c c } X & f \\\hline 5 & 2 \\4 & 2 \\3 & 3 \\2 & 5 \\1 & 2\end{array}$$
a.N
b.ΣX
c.ΣX²