Final answer:
The total completion time of a project with several activities depends on the interdependencies of the tasks, which might allow for concurrent work or require a sequential process.
Step-by-step explanation:
The student has inquired about calculating the total completion time for a project with four activities with different durations and potential interdependencies. To accurately determine the total completion time of the project, one must consider the sequence of activities and any dependencies that may require one task to be completed before another can begin. For instance, if activities need to be completed sequentially, you would add up the durations. However, if some activities can occur concurrently, the project could be completed in less time than the sum of individual durations.