A gas network construction company is at the end of a project, with 9 activities remaining to be performed. activities,

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A gas network construction company is at the end of a project,
with 9 activities remaining to be performed. activities, whose
precedence, execution time and costs are shown in the following
table. table below:
a) Determine the critical path(s) and execution time of the
project, using the normal execution time for each activity.
normal execution time for each activity.
b) Calculate the cost slopes of each activity of the project.
c) How much will it cost to advance the project execution time by 3
days?
d) Make a TIME - COST graph.