Given the following times for the activities, compute the variance and standard deviation for activity D: Activity Optimistic Time (a) Most Likely Time (m) Pessimistic Time (b) A 5 6 7 B 1 3 5 C 1 2 4 D 2 4 6 variance = 0.44 and standard deviation = 0.66 variance = [(6 2) / 6] and standard deviation = [(6 2) / 6] variance = 0.66 and standard deviation = 0.44 variance = 0.11 and standard deviation = 0.33