Fundamentals of operation research

A: Governing principle: safety availability claims must be conservative and auditable. Applied here: constant-rate Markov models trade some realism for traceability and avoid embedding unproven aging assumptions into SIL decisions. Distractor trap: engineers who know wear-out exists often jump to Weibull, but misapply it where the standard prefers defendable simplicity.

A: Governing principle: Little’s Law links WIP, throughput, and flow time. Applied here: 8 units/day times 6 days lands near 48 units, and rough variability doesn't change the order. Distractor trap: engineers conflate lean targets with physics and undercount WIP by assuming ideal flow.

A: Governing principle: match uncertainty representation to decision needs. Applied here: PERT keeps the same precedence structure while explicitly modeling duration spread. Distractor trap: CPM veterans know the network well and forget that duration uncertainty, not logic, is the problem.

A: Governing principle: EOQ balances ordering and holding via a square root. Applied here: sqrt(2×1200×300 / 20) lands just under 200, even with coarse inputs. Distractor trap: engineers linearize the costs mentally and miss how weakly EOQ reacts to estimation error.