The average value is 5.

Variance is the average minus each number, and vice versa. Because there is a square, it is all the same. Then square it and add it together to calculate the average.

5- 1=4, the square is 16, and so on, 1, 4,9.

It adds up to 30,30/4 = 7.5.

The variance is 7.5.