Problem: The activities in the table apply to the computerization of a company’s accounting system, presently operated manually.
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Activity
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Expected Completion Time
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a
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Select computer
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2 months
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b
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Assemble and install computer
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6
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c
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Design data input forms
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2
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d
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design output report forms
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2
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e
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write main processing programs
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6
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f
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write input routines
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4
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g
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write output routines
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3
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h
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generate accounting data bank
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3
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i
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test and revise system
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2
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All of the program routines can be written independently before the computer is installed and can be debugged using computer time rented from another company. No programs or routines can be written until the particular computer model has been selected, although forms and reports can be designed while alternative computers are being evaluated. No input or output routines can be written until the corresponding forms have been designed. The main processing programs and input routines are required to establish the accounting data bank, which can be created on rental equipment. The final activity before implementation is complete is to test and revise the system.
(a) Construct a PERT network for converting the accounting system
(b) What is the earliest time that the conversion can be finished assuming that the completion times are certain?
(c) Establish the early and late starting and finishing times for each activity. Which activities are critical?