The GATE Grind

GATE 2020 ME (ME1) – Question 23

Operations Research · Network flow models, PERT and CPM · 1 mark · Multiple choice

In the Critical Path Method (CPM), the cost–time slope of an activity is ______.

  1. (Crash cost − Normal cost) / Crash time
  2. Normal cost / (Crash time − Normal time)
  3. Crash cost / (Crash time − Normal time)
  4. (Crash cost − Normal cost) / (Normal time − Crash time)

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Show answer and explanation

Correct answer: (D) (Crash cost − Normal cost) / (Normal time − Crash time)

Explanation

Crashing adds cost while reducing duration. Cost per unit time saved is the incremental cost divided by normal duration minus crash duration. Both increments are positive under usual assumptions. **Answer: D.**