Respuesta :
The minimum total cost for Normal duration is $4850, for crash C by 1 period if $4795, for crash A by 2 period is $4735, for crash C and B by 1 period if $4760, for crash C and D by 1 period is $4785 and crash D and E by 1 period is $4815.
For activity A,B,C,D,E,F,G,H and I
The normal duration are 7,6,8,10,6,4,4,7 and 2 respectively
The crashed duration are 5,5,5,7,4,3,2,4 and 2 respectively.
The normal cost are $500, $550, $800, $1,200, $600, $500, $700, $650 and $300 respectively
The crashing cost are $640, $630, $935, $1,400, $700, $590, $1000, $950 and $300 respectively
The time available for crashing = normal duration - crashed duration.
Thus for each A,B,C,D,E,F,G,H and I, are 2,1, 3,3,2,1,2,3 and 0 respectively.
The cost of crashing per period= (Crashing cost-normal cost)/ periods available for crashing.
Thus for each it is $70, $80, $45, $80, $50, $90, $150, $100 and none
Steps for crashing a project
1) Select the critical path and find the process with the least cost of crashing per week
2) If there are multiple critical paths, look for processes that are common, common process may have low effective cost as common process crashes more than 1 path at once
3) one can only crash an activity depending on the time available for crashing. If an activity is only crashed that much time, choose another activity.
4) add the cost of crashing later
Crashing
For path, ABDG1- The normal duration is 29, crash C by 1 period is 29, crash A by 2 period is 27, crash C and B by 1 period is 26, crash C and D by 1 period is 25, crash D and E by 1 period is 24
For path, ABEHI- The normal duration is 28, crash C by 1 period is 28, crash A by 2 period is 26, crash C and B by 1 period is 25, crash C and D by 1 period is 25, crash D and E by 1 period is 24
For path, ACEHI- The normal duration is 30, crash C by 1 period is 29, crash A by 2 period is 27, crash C and B by 1 period is 26, crash C and D by 1 period is 25, crash D and E by 1 period is 24
For path, ACFGI- The normal duration is 25, crash C by 1 period is 24, crash A by 2 period is 22, crash C and B by 1 period is 21, crash C and D by 1 period is 20, crash D and E by 1 period is 20
For path, ACFH1- The normal duration is 29, crash C by 1 period is 29, crash A by 2 period is 27, crash C and B by 1 period is 26, crash C and D by 1 period is 25, crash D and E by 1 period is 24
For path, ABDG1- The normal duration is 28, crash C by 1 period is 27, crash A by 2 period is 25, crash C and B by 1 period is 24, crash C and D by 1 period is 23, crash D and E by 1 period is 23
The cost for Normal duration is $4850, for crash C by 1 peiord if $45, for crash A by 2 period is $140, for crash C and B by 1 period if $125, for crash C and D by 1 period is $125 and crash D and E by 1 period is $130.
The minimum total cost is
$4850, 4795, 4735, 4760, 4785 and 4815 respectively.