The Lockhead Aircraft Co. has a defense contract for a project to be completed i

Question

The Lockhead Aircraft Co. has a defense contract for a project to be completed in 100 weeks. The project involves 10 activities (labelled A, B, ..., J) with precedence relationship in network (b). The estimate (in terms of number of weeks) of the duration of each activity is in the table below. Find the estimate of the mean and variance of the duration of each activity. Obtain the critical path. Find the approximate probability that the project wil finish within 100 weeks. Optimistic 28 22 26 14 32 40 12 16 26 12 Most likely 32 28 36 16 32 52 16 20 34 16 Pessimistic 36 32 46 18 32 74 24 26 42 30

Explanation / Answer

In order to find the mean estimated and variace of the duration of each activity we use below formula

mean = (to + 4tm + tp)/6

variance = ((tp - to)/6)^2

Below is the table gives value for each activity

Different possible paths are

Hence Critical path is BFJ with completion time of 99 weeks

Variance of the critical path = 43.8889 hence std. dev. = 6.6249

Probability that the project will complete within 100 weeks P(X<100)

P(X<100) = P(z < (100 - 99)/6.6249) = P(z < 0.151) = 0.56

Activity to tm tp estimated time Variance A 28 32 36 32.0000 1.7778 B 22 28 32 27.6667 2.7778 C 26 36 46 36.0000 11.1111 D 14 16 18 16.0000 0.4444 E 32 32 32 32.0000 0.0000 F 40 52 74 53.6667 32.1111 G 12 16 24 16.6667 4.0000 H 16 20 26 20.3333 2.7778 I 26 34 42 34.0000 7.1111 J 12 16 30 17.6667 9.0000

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.