In the time-cost optimization, using CPM method for network analysis, the crashing of activities along the critical path is done starting with the activity having the
- ALeast Cost Slope.Correct
- BLeast Duration.
- CLongest Duration.
- DHighest Cost Slope.
Solution
Concept
Crashing means reducing project duration at the minimum additional cost. To save money, we always shorten the critical activity that costs the least per day.
Formula
Cost Slope = (Crash Cost - Normal Cost) / (Normal Time - Crash Time)
Step-by-step solution
1. In project management, only critical activities determine the total project time. 2. Therefore, to reduce project duration, we must crash activities located on the critical path. 3. Cost slope is the extra direct cost needed to reduce the time by one unit (e.g., per day). 4. To keep total project cost as low as possible, we start crashing the critical activity that has the minimum extra cost per day, which is the least cost slope. Answer: (A) Least Cost Slope.
Explanation
Cost slope represents the extra cost incurred per unit of time saved. In time-cost optimization, our goal is to decrease project time with minimum extra cost. Hence, activities on the critical path with the lowest cost slope are crashed first.
Why the other options are wrong
B: Duration does not indicate the cost required to speed up an activity. C: Longest duration only tells how long an activity takes, not how cheaply it can be crashed. D: Crashing with the highest cost slope adds the maximum cost, which violates cost optimization.
Shortcut
Minimum extra cost means minimum slope; always pick least cost slope first.
Common mistake
Students often confuse duration with cost and incorrectly choose the activity with the longest or least duration.
Correct answer: A) Least Cost Slope.