The Lockhead Aircraft Co. is ready to begin a project to develop a new fighter airplane for the U.S. Air Force. The company’s contract with the Department of Defense calls for project completion within 100 weeks, with penalties imposed for late delivery.

The project involves 10 activities (labeled A, B, . . . , J), where their precedence relationships are shown in the following project network.

T

(a) Find the estimate of the mean and variance of the duration of each activity.

(b) Find the mean critical path.

T

(c) Find the approximate probability that the project will finish within 100 weeks.

(d) Is the approximate probability obtained in part

(c) likely to be higher or lower than the true value?