Question

The following table of probabilistic time estimates (in weeks) and activity predecessors are provided for a project.

Time Estimates (weeks)

Activity	a	m	b	Activity Predecessor
A	3	5	7	--
B	4	8	10	A
C	2	3	5	A
D	6	9	12	B, C
E	5	9	15	D

Table 9.2

Reference: Ref 9-2

Using Table 9.2, the earliest start (ES) time for activity D is

Select one:

A. 21.67 weeks.

B. 8.17 weeks.

C. 12.67 weeks.

D. 18.33 weeks.

Answer 1

Expected time of an activity = (optimistic + (4 * most likely) + pessimistic) / 6

Most likely(m) Activity Optimistic(a) Pessimistic (b) Expected time A 3 5 7 5 8 10 B 4 7.67 3.17 C 2 3 D 12 5 E 15 9.33 LO LO CO LO

Netuark Es- Barly Start Ls-Lae Stezs LE Lae fiaish FnishミEf Easly ES EF Lsl LE S 12.6 12-4 21-6f 2131 12-47 21-457 E1-8 S

Early start time of activity D is 12.67. Hence the correct option is c. 12.67