Question

The erection of a steel electrical tower that has 5 levels involves the task durations below. Each of the 5 levels must have its steelwork erected, have stabilising wires connected and then be painted. After all the 5 levels are completed, the electrical wires will be connected to the top of the tower:

Erect one level of steelwork = 2 days

Connect the stabilising wires to one level of steelwork = 3 days

Paint one level of steelwork = 2 days

Install the electrical wires to the top level of the tower = 3 days

The stabilising wires cannot begin to be connected to a level until the steelwork erection for that level has completed. The stabilising wires cannot be connected to a level until the connection of the stabilising wires to the previous level has completed. No more than one level of steel work can be erected above a level without completed stabilising wires. The electrical wires cannot be installed to the top level of the tower until all steelwork, stabilising and painting has completed. What is the minimum time in which the electrical tower can be completed? (Answer in days)

Answer 1

Erection of steel electrical tower

a. steelwork - activity A - 2 days - A1, A2 ....A5

b. stabilizing wires - activity B - 3 days - B1,B2......B5

c. painting - activity C - 2 days - C1,C2.....C5

d. electrical wires - activity D - 3 days - D.

conditions

1. B1 can only start when A1 is complete

2. B2 can only start when B1 is complete

3. A2 can start after A1 is complete and B1 is ongoing but A3 can only start when B1 is complete.

4. C1 starts when A1 and B1 both are complete.

5. D can start only when A,B, and C off all 5 levels are completed.  

therefore it will take   22 days to complete the job.

do give thambs up .