Question

Problem 15-7

Consider the following table of precedence relationships for a portion of a house building project:

	Task	Duration Estimates		Immediate Predecessor(s)
A	Prepare Site	3	days	None
B	Install Rough Plumbing	2	days	Prepare Site
C	Pour Concrete Foundation	3	days	Install Rough Plumbing
D	Concrete Curing Time	4	days	Pour Concrete Foundation
E	Preassemble Wall Frames	6	days	None
F	Erect Wall Frames	2	days	Preassemble WF, Cure Concrete
G	Install Roof	1	day	Erect Wall Frames
H	Install Wiring	6	days	Install Roof
I	Install Exterior Siding	5	days	Install Roof
J	Install Insulation	3	days	Install Exterior Siding
K	Hang Drywall	1	day	Install Insulation, Install Wiring
L	Windows	1	day	Hang Dry Wall
M	Paint Interior	7	days	Install Windows
N	Paint Exterior	3	days	Install Exterior Siding
O	Level Yard	2	days	Cure Concrete
P	Landscape Yard	4	days	Level Yard

a-1. Calculate earliest start and finish for each task. (Leave no cells blank - be certain to enter "0" wherever required.)

a-2. Calculate slack for every project activity. (Leave no cells blank - be certain to enter "0" wherever required.)

a-3. Identify the critical path..

	A-B-C-D-O-P
	A-B-C-D-F-G-I-J-K-L-M
	A-B-C-D-F-G-I-N
	A-B-C-D-F-G-H-K-L-M
	E-F-G-I-J-K-L-M
	E-F-G-H-K-L-M
	E-F-G-H-K-L-M

c-1. What will happen to the project if the materials needed for the frame preassembly are not available until the second day of the project?

	Would delay the start of F
	Would delay the start of A
	The project will not be affected

c-2. What if the materials were delayed until the tenth day?

	The project will not be affected
	Would delay the start of A
	Would delay the start of F

Answer 1

CPM refers to critical path method where shortest path is taken to plan the project. The steps in CPM schedule include: -

• Individual activities are specified.
• Sequence of those activities are determined.
• Drawing a network diagram.
• Completion time of each activity is estimated.
• Critical path is identified.
• CPM diagram is updated.