#20

1- A series of activities must be completed in a coordinated fashion to complete a landscaping overhaul. The following table shows the activities their optimistic, most likely and pessimistic durations and their immediate predecessors

DAYS

Activity A m b Immediate Predecessors

A 4 8 12 —

B 4 10 13 A

C 7 14 18 B

D 9 16 20 B

E 6 9 12 B

F 2 4 6 D,E

G 4 7 13 C,F

H 3 5 7 G

I 2 3 4

G,H

A- Determine the expected times and variances for each activity

B- Construct a project network for this problem

C- Determine the EST, EFT, LST, LFT and slack for each activity. Also determine the critical path and project completion time.

D- What is the probability that the project will be finished in less than 57 days?

E- What is the probability that the project will need at least 50 days?

# 22

The expected project completion time for the construction of a pleasure yacht is 21 months, and the project variance is 6. What is the probability that the project will:

- Require at least 17 months?
- Be completed within 20 months?
- Require at least 23 months?
- Be completed within 25 months?

# 30

Bowman Builders manufactures steel storage sheds for commercial use, Joe Bowman, president of Bowman Builders, is contemplating producing sheds for home use. The activities necessary to build an experimental model and related data are given in the table on the next page. The project completion time using standard times is 14 weeks. How much does it cost to reduce the duration of this project from 14 weeks to 10 weeks?

Activity Immediate Predec. Standard time Stand. Cost Crashtime(weeks) CrashCost

A — 3 1,000 2 1,600

B — 2 2,000 1 2,700

C — 1 300 1 300

D A 7 1,300 3 1,600

E B 6 850 3 1,000

F C 2 4,000 1 5,000

G &n

bsp; D,E 4 1,500 2 2,000