PERT Analysis MCQ with answer and solution

Concept

Types of float in CPM network analysis

Formula

IF = E_j - L_i - t_ij

Step-by-step solution

1. Recall CPM network float definitions: - Maximum available time = L_j - E_i. - Minimum available time = E_j - L_i. 2. Independent Float (IF) is the excess of minimum available time over the activity duration (t_ij): IF = (E_j - L_i) - t_ij. 3. Total float is L_j - E_i - t_ij, and Free float is E_j - E_i - t_ij. 4. Therefore, option B (Independent Float) matches the exact definition. Answer: B

Explanation

Independent Float is defined as the excess of minimum available time over the activity duration: IF = (E_j - L_i - t_ij). It represents the amount of time an activity can be delayed without affecting the schedule of any preceding or succeeding activities in the CPM network.

Why the other options are wrong

A) Total Float is the excess of maximum available time over activity duration (L_j - E_i - t_ij). C) Free Float is the excess of available time when both events occur at earliest times (E_j - E_i - t_ij). D) Interfering Float is the difference between Total Float and Free Float.

Shortcut

Minimum available time - duration = Independent Float; Maximum available time - duration = Total Float.

Common mistake

Selecting Total Float (excess of maximum available time) or Free Float (delay without affecting subsequent earliest starts).