Table $11-2$

The following represents a project with four activities. All times are in weeks.

Activity Immediate

Predecessor Optimistic

Time Most Likely

Time Pessimistic

Time

A $-2814$

B $-888$

C A $6918$

D B $51117$

According to Table $11-2,$ there are four activities in the project. Assume the normal distribution is appropriate to use to determine the probability of finishing by a particular time. If you wished to find the probability of finishing the project in $20$ weeks or fewer, it would be necessary to find the variance and then the standard deviation to be used with the normal distribution. What variance would be used?