Hard Rock

A small renovation of a Hard Rock Cafe gift shop has six activities (in hours). For the following estimates of a, m, and b, calculate the expected time and the standard deviation for each activity:
Activity           a         m         b
A              11        15       19
B              27        31       41
C              18        18       18
D                8        13       19
E              17        18        20
F              16        19        22