Precedence Tables

A project has the following tasks.
A: no preceding task, $\displaystyle 6$ hours
B: no preceding task, $\displaystyle 4$ hours
C: preceded by A, $\displaystyle 5$ hours
D: preceded by B, $\displaystyle 6$ hours
E: preceded by C and D, $\displaystyle 3$ hours
State which tasks can be started immediately.

A project has the following tasks.
A: no preceding task, $\displaystyle 6$ hours
B: no preceding task, $\displaystyle 4$ hours
C: preceded by A, $\displaystyle 5$ hours
D: preceded by B, $\displaystyle 6$ hours
E: preceded by C and D, $\displaystyle 3$ hours
State which tasks must be finished before task E can start.

In a precedence table, a task has no entry in the 'preceding task' column.
Explain what this tells you about the task.

A project has the following tasks.
A: no preceding task, $\displaystyle 6$ hours
B: no preceding task, $\displaystyle 4$ hours
C: preceded by A, $\displaystyle 5$ hours
D: preceded by B, $\displaystyle 6$ hours
E: preceded by C and D, $\displaystyle 3$ hours
Calculate the minimum time needed to complete the project.

A project has the following tasks.
A: no preceding task, $\displaystyle 3$ hours
B: no preceding task, $\displaystyle 5$ hours
C: preceded by A, $\displaystyle 4$ hours
D: preceded by A, $\displaystyle 2$ hours
E: preceded by B, $\displaystyle 6$ hours
F: preceded by C and D, $\displaystyle 3$ hours
G: preceded by E and F, $\displaystyle 2$ hours
Calculate the minimum time needed to complete the project.

A project has the following tasks.
A: no preceding task, $\displaystyle 3$ hours
B: no preceding task, $\displaystyle 5$ hours
C: preceded by A, $\displaystyle 4$ hours
D: preceded by A, $\displaystyle 2$ hours
E: preceded by B, $\displaystyle 6$ hours
F: preceded by C and D, $\displaystyle 3$ hours
G: preceded by E and F, $\displaystyle 2$ hours
State the tasks that lie on the longest route through the project.

The tasks in a project have durations totalling $\displaystyle 40$ hours, but the project can be completed in $\displaystyle 23$ hours.
Explain how this is possible.

Task F is preceded by tasks C and D.
Task C finishes after $\displaystyle 11$ hours and task D finishes after $\displaystyle 14$ hours.
State the earliest time task F can start, and explain your answer.