Consider the following Normal costCrash cost 900 300 500 900

Consider the following: Normal costCrash cost 900 300 500 900 1000 ActivityNormal time Crash time Predecessor 1000 400 600 1200 1600 4 13 Calculate the minimum cost of crashing by 4 days Your Answer:

Solution

The precedence diagram as follows :

                                    A

                               B

                                        C

                                    D

                                         E

The possible paths and their corresponding normal durations as follows :

A-D = 6 + 5 = 11 days

B = 8 days

C-E = 4 + 8 = 12 days

The critical path ( i.e. the path with longest duration ) is C-E .

Normal duration of the project ( i.e. Duration of the critical path = 12 days

For the project duration to be crashed by 4 days from normal duration of 12 days:

Crash A from 6 days to 5 days (i.e. Reduction of 1 day) at a crash cost of 1000

Crash D from 5 days to 3 days (i.e. reduction of 2 days) at a crash cost of 1200

Crash C from 4 days to 3 days (i.e. reduction of 1 days) at crash cost of 600

Crash E from 8 days to 5 days (i.e. reduction of 3 days) at a crash cost of 1600

Note: Duration of activity B remains unchanged at 8 days at normal cost of 300

Thus total cost of crashing by 4 days as follows :

Type of cost

Total :

MINIMUM COST OF CRASHING BY 4 DAYS IS 4700

A	B	C
D	E