I'm lost on how to get the SS quantity for the last column. I know the T= 218, and M= 36.33

Reward Type 1	Reward Type 2	Reward Type 3	Reward Type 4	Person Totals (P)
3 5 6 2 1 2	6 7 9 7 11 6	9 10 15 12 11 10	12 13 15 18 15 13	30 35 45 39 38 31
T=19; M=3.17; SS=18.83	T=46; M=7.67; SS=19.33	T=67; M=11.17; SS=22.83	T=86; M=14.33; SS=23.33