What is the expected activity cost for a project having a most likely cost of $140, a best case scenario of $115, and a worst case scenario of $165?

Question

Options

• A$115
• B$138
• C$140
• D$165

• A
  16% (4)
• B
  4% (1)
• C
  72% (18)
• D
  8% (2)

Explanation

Option C ($140) is correct because the standard PERT (Program Evaluation and Review Technique) formula for expected cost is (Optimistic + 4 × Most Likely + Pessimistic) ÷ 6, which yields (115 + 560 + 165) ÷ 6 = 840 ÷ 6 = $140. In this case, the optimistic and pessimistic estimates are equally spread around the most likely value ($25 each), so the weighted result coincides with the most likely figure.

Why the distractors are wrong:

• A ($115) is simply the best-case (optimistic) estimate - no weighting applied.
• B ($138) doesn't result from any standard estimation formula; it may tempt test-takers who misremember the weights or miscalculate.
• D ($165) is the worst-case (pessimistic) estimate - again, no formula applied.

Memory tip: Think of PERT as "1-4-1" - the most likely estimate gets 4 votes, while optimistic and pessimistic each get 1 vote, all divided by 6. This reflects real-world logic: the most experienced estimate deserves the most weight.

No community discussion yet for this question.