PERT Analysis MCQ with answer and solution

Concept

Calculation of expected time in PERT

Formula

(t_o + 4·t_m + t_p) / 6

Step-by-step solution

1. Given optimistic time to = 6 days, pessimistic time tp = 16 days, and most likely time tm = 8 days. 2. Expected time equation in PERT is te = (to + 4 × tm + tp) / 6. 3. Substitute the values: te = (6 days + 4 × 8 days + 16 days) / 6 = 54 days / 6 = 9 days. Answer: A

Explanation

The expected time in PERT analysis is calculated using the weighted average formula Te = (a + 4m + b) / 6, where a is optimistic time, m is most likely time, and b is pessimistic time. Substituting the given values gives Te = (6 + 4(8) + 16) / 6 = 54 / 6 = 9 days. Thus, 9 days is the correct expected completion time.

Why the other options are wrong

B) Applying the PERT expected time formula (6 + 4×8 + 16)/6 yields 9 days, not 5 days. C) 6.5 days results from a calculation error and does not match the weighted average result of 9 days. D) 7 days is incorrect as the formula calculates expected time as (6 + 32 + 16) / 6 = 9 days.

Shortcut

PERT Expected time = (Optimistic + 4 × Most Likely + Pessimistic) / 6.

Common mistake

Calculating a simple arithmetic average instead of applying the weighted PERT formula (to + 4tm + tp) / 6.