Hey VinceW.

You are right in that the variance is too high.

The sum of squares is (30*31*61)/6 but then multiplying this by 1/30 gives

> 30*31*61/(6*30)

[1] 315.1667

Our variance is now 315.1667 - (31/2)^2 or

> 30*31*61/(6*30) - (31/2)^2

[1] 74.91667