5.4See File Problem 5-4.Xls

CHAPTER 5

5.4See file Problem 5-4.xls

Expected completion time = 89 days

5.7See file Problem 5-7.xls

P(Finish within 90 days) = .590439

Thus P(Finish later than 90 days) = 1 - .590439 = .409561

5.8See files Problem 5-8a.xls and Problem 5-8b.xls

a.28 weeks

b. Crash A 4 weeks, B 3 weeks, E 2 weeks, F 5 weeks, G 4 weeks; additional cost = $29,950 - $24,600 = $5,350

5.9See file Problem 5-9.xls

Switching to Glidestone would cost $28,750. So Keith should switch to Glidestone.

Now, crash A 4 weeks, B 3 weeks, E 2 weeks, F 7 weeks, G 1 week.

5.11See file Problem 5-11.xls

From the output convert times beginning at 10:00PM.

Activity ES EF LS LF SLACK

A10:00PM11:20PM10:00PM11:20PM0

B10:00PM11:00PM12:00AM 1:00AM 2 hours

C11:20PM 1:00AM11:20PM 1:00AM0

D11:20PM 1:00AM 3:40AM 5:20AM 2 hours, 20 min.

E11:20PM12:20AM12:40AM 1:40AM 1 hour, 20 min.

F 1:00AM 1:40AM 1:00AM 1:40AM0

G 1:00AM 1:20AM 3:00AM 3:20AM 2 hours

H 1:40AM 2:20AM 4:40AM 5:20AM 3 hours

I 1:40AM 2:40AM 4:40AM 5:40AM 3 hours

J 1:40AM 3:20AM 1:40AM 3:20AM0

K 2:20AM 2:40AM 5:20AM 5:40AM 3 hours

L 3:20AM 5:40AM 3:20AM 5:40AM0

b.A schedule must have no job started before its ES or finished after its LF. If Worker 1 does only the activities on the critical path then one such schedule is:

Schedule for Worker 1Schedule for Worker 2

A 10:00PM - 11:20PMB 10:00PM - 11:00PM

C 11:20PM - 1:00AME 11:20PM - 12:20AM

F 1:00AM - 1:40AMD 12:20AM - 2:00AM

J 1:40AM - 3:20AMG 2:00AM - 2:20AM

L 3:20AM - 5:40AMH 2:20AM - 3:00AM

I 3:00AM - 4:00AM

K 4:00AM - 4:20AM

5.12See file Problem 5-12.xls

104 months

b.(i) 5 months (ii) 3 months

c.(i) .000173 (shown); (ii) .012674; (iii) .185547; (iv) .672640

5.16See file Problem 5-16.xls

a.21 weeks

b. G (Lodging and Transportation) has 11; C (Hire Security) and J (Concessions) have 5 weeks slack each.

c..000023 (not shown)

d.By trial and error on the template --- 26.144 weeks (shown)

For those familiar with the Goal Seek option in the Tools menu of Excel, one can generate a solution as follows:

5.17See files Problem 5-17Boeing.xls and Problem 5.17MDD.xls

BOEING

MCDONNELL-DOUGLAS

a. McDonnell-Douglas (Prob. = .960423 vs. .947353 for Boeing)

b.Boeing (Expected completion time = 54 vs. 55 for McDonnell-Douglas)

5.18See file Problem 5-18.xls

a.40days; The sum of the activity costs is $356,100

Total Delay

b.(i)H is on the critical path2 days

(ii)C has 3 days slack0 days

(iii)F has 10 days slack1 day

(iv)F has 10 days slack4 days

(v)G has 3 days slack0 days

(vi)C has 3 days slack, F has 10 days slack, not on same path1 day

(vii)C and G are on same path with a total of 3 days slack1 day

5.20See files Problem 5-20ab.xls and Problem 5-20c.xls

a.Expected completion = 89 days; critical path = C-D-F-G-I-K

Earliest/latest start/completion dates:

Earliest EarliestLatestLatest

ActivityStartFinishStartFinish

AJune 1June 4June 6June 9

BJune 1June 6June 10June 15

CJune 1June 7June 1June 7

DJune 7June 15June 7June 15

EJune 4June 10June 9June 15

FJune 15July 17June 15July 17

GJuly 17August 8July 17August 8

HJuly 17 July 28July 23 August 4

IAugust 8August 24August 8August 24

JJuly 28August 17August 4August 24

KAugust 24August 29August 24August 29

b..924136

c.See file Problem 5-20c to find the probability of completing in 99 days if the $3500 is spent.

If the $3500 is not spent (part (b)), the expected total cost is:

.924136(0) + .075864($120,000) =$9,103.68

If the $3500 is spent (part (c)), the expected total cost is:

.977912(0) + .022088($120,000) + $3,500 =$6,150.56

Yes -- Spend the $3,500

5.21See file Problem 5-21.xls

See schedule above that meets the deadline at a cost of $89,000.

5.23See files Problem 5-23a.xls and Problem 5-23b.xls

a.$476,500 -- see above for schedule

It is infeasible -- the project cannot be completed in less than 18 weeks.

5.24See file Problem 5-24.xls

135.5833 days

5.27See file Problem 5-27a.xls and Problem 5-27c.xls

a. 36.33333 weeks; A-B-F-H-I

b..441705

c.Would not spend $1000 to move the files alone since move files (Activity G) is not on the critical path.

If $1000 was spent on moving equipment, the three time estimates for activity F are now 1, 2, and 3. In this case, from file Ch5.27c-equip (not shown), the new critical path is A-B-G-H-I and P(Finish in 36) = .556513.

Note that G is now on the critical path, so now it worth exploring spending another $1000 (for $2000 total) to also cut activity G's three time estimates to .5, 1, and 2.5. In this case, from file Ch5.27c-both (not shown), the critical path is once again A-B-F-H-I and P(Finish in 36) = .615351.

Expected Cost = Prob(Finish in 36)($0) + P(Not Finish in 36)($5000) + Hiring Costs

Expected Cost(Neither) = .441705($0) + .558295($5000) + $0 = $2791.48

Expected Cost(Equipment) = .556513($0) + .443487($5000) = $1000 = $3217.44

Expected Cost(Both) = .615351($0) + .384649($5000) + $2000 = $3923.25

DO NOT HIRE EITHER SET OF MOVERS.

5.30See file Problem 5-30.xls

a.Critical Path: A - C - E - G= 30 days = 4.333333 days

b.(i) 5 days (0 slack)

(ii)Project not delayed (8 days slack)

(iii)4 days (1 day slack)

(iv)4 days (1 day slack)

(v)4 days (B and D not on the same path)

(vi)9 days (D and F are on the same path)

5.33See file Problem 5-30.xls and Problem 5-33.xls

If Stacey does not spend the $3000

See file Ch5.30.xls and enter 35 into cell F6 (not shown)

P(finish in 35 days) = .875718

Thus the expected cost is (.875718)(0) + .124282(100,000) = $12,428.20

If Stacey does spend the $3000

If Stacey does spend the $3000

See file Ch5.33.xls and enter 35 into cell F6 (shown above)

P(finish in 35 days) = .933868

Thus the expected cost is (.933868)(0) + .066132(100,000) = $6,613.20

+ extra $3000 =$3,000.00

TOTAL =$9,613.20

$9,613.20 < $12,428.20, so Stacey should spend the extra $3000.

5.37See files Problem 5-37a.xls and Problem 5-37c.xls

a. See below.

b.36 weeks; B - I

c.(i) Activity H has 8 weeks slack; delaying it 10 weeks will delay the project 2 weeks.

Cost = $6,000 + 2($5,000) = $16,000

(ii)Since activity H has 8 weeks slack, an extra 4 weeks will not delay the project

Cost = $17,500

(iii)Change E to 11 and H to 6 and re-solve. The project now takes 37 weeks (not shown). Thus the cost of this option is: $4000 + $5500 + 1($5000) = $14,500.

The senior center should use its own landscaping crew.

5.38See file Problem 5-38.xls

a.No, the expected time = 17 weeks

b.H has 2 weeks slack; delaying it by 3 weeks will delay the project by 1 week.

c.D has 2 weeks slack; delaying it by 3 weeks will delay the project by 1 week.

d..339639

Chapter 5 - 1