Hint: prepare a three-columned table, one for (x), another for the (deviation), and the last for the (squared-deviation). Sum of (x) = 15x, algebraic sum of (deviation) = zero (0) Sum of (squared-deviation) = 10x\(^2\) Variance = \(\frac{∑(squared-deviation)}{\text{n}}\) = \(\frac{10x^2}{5}\) = 2x\(^2\)