Download presentation

Published byLauren Apps Modified over 2 years ago

1
**Problem 13-28 Activity Immediate Predecessor a m b A - 9 10 11 B 4 16**

The estimated times (in weeks) and immediate predecessors for the activities in a project are given in the following table. Assume that the activity times are independent. Activity Immediate Predecessor a m b A - 9 10 11 B 4 16 C D 5 8 Kelly Devilbiss - Problem 13-28

2
**(a) Calculate the expected time and variance for each activity.**

b Expected time t= [(a+4m+b)/6] Variance [(b-a)/6]2 A 9 10 11 4/36 B 4 16 144/36 C D 5 8 36/36 Kelly Devilbiss - Problem 13-28

3
**Kelly Devilbiss - Problem 13-28**

(b) What is the expected completion time of the critical path? What is the expected completion time of the other patient in the network? Critical Path AC takes 20 weeks Critical Path BD takes 18 weeks Kelly Devilbiss - Problem 13-28

4
**Kelly Devilbiss - Problem 13-28**

What is the variance of the critical path? What is the variance of the other path in the network? Critical Path AC: σ2CP = σ2A + σ2C = 4/36 + 4/36 = 8/36 = 0.222 Critical Path BD: σ2CP = σ2B + σ2D = 144/ /36 = 180/36 = 5 Kelly Devilbiss - Problem 13-28

5
**Kelly Devilbiss - Problem 13-28**

(d) If the time to complete path A-C is normally distributed, what is the probability that this path will be finished in 22 weeks or less? t = 20 variance (σ2) = 0.222 standard deviation (√0.222) = 0.47 P(x ≤ 22) = P[(22 – 20)/0.47] = 4.26 Using Appendix A: 4.26 = 1.00 Kelly Devilbiss - Problem 13-28

6
**Kelly Devilbiss - Problem 13-28**

(e) If the time to complete path B-D is normally distributed, what is the probability that this path will be finished in 22 weeks or less? t = 18 variance (σ2) = 5 standard deviation (√5) = 2.24 P(x ≤ 22) = P[(22 – 18)/2.24] = 1.79 Using Appendix A: 1.79 = Kelly Devilbiss - Problem 13-28

7
**Kelly Devilbiss - Problem 13-28**

(f) Explain why the probability that the critical path will be finished in 22 weeks or less is not necessarily the probability that the project will be finished in 22 weeks or less. Path B-D has more variability and has a higher probability of exceeding 22 weeks. Kelly Devilbiss - Problem 13-28

Similar presentations

OK

Operations and Project Management Session 3 Extra Some Additional Details on CPM and PERT.

Operations and Project Management Session 3 Extra Some Additional Details on CPM and PERT.

© 2017 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on central limit theorem applet Download ppt on turbo generators Ppt on bombay stock exchange Ppt on cartesian product of three Ppt on world population Ppt on number system for class 8 Disaster management ppt on tsunamis Ppt on chapter 12 electricity providers Ppt on microsoft dynamics nav erp Free ppt on small scale industries in india