The estimated times (in weeks), immediate predecessors for the activities, normal cost, crash cost and crash time in a project are given in the following table. Assume that the activity times are independent.

Activity

Immediate predecessors

a

m

b

t

ES

EF

LS

LF

SLACK

A

-

9

10

11

B

A

4

10

16

C

A

8

9

10

D

B

5

8

11

E

B, C

10

12

14

F

D

8

10

12

G

D, E

6

7

8

What is the probability that the project will be completed in 42 weeks or less?

a.67%

b.92%

c.74%

d.68%