Test what must follow in every allowed case.
Review implications, contraposition, ordering, exclusive choices and constrained selections. Finite models and counterexamples explain each key without an ability label.
Six original tasks each count one correct answer. Your count out of six describes these tasks under your practice conditions, not a percentile, IQ estimate or fixed ability band. All worked answers and this complete guide remain available at every count.
What is guaranteed by these rules?
The six tasks supply exact puzzle rules: one mark implies another, a missing consequence rules out its required cause, labels occupy distinct ordered positions, exactly one light is on, and a selection must meet several conditions together. Read these as formal constraints for the exercise. Real systems may have exceptions; the puzzle does not inspect or certify them.
A counterexample blocks a converse
Suppose every red card is stamped, and a card is stamped. It need not be red: a blue stamped card satisfies the rule too. That one allowed case defeats the claim that stamping guarantees red. By contrast, a card with no stamp cannot be red under the supplied rule. Distinguish the converse from the contrapositive rather than treating both as a reversed sentence.
Check scope and exact wording
For “must follow,” seek a statement true in every admissible case, not merely one possible case. “Exactly one” differs from “at least one.” A distinct-position ordering excludes ties only because the prompt says so. For a selection, an option that meets one condition but violates another is invalid. The worked explanations identify the particular constraint each missed option breaks.
Enumerate a small puzzle
For two yes-or-no properties, write all four combinations, cross out those that break a stated rule and inspect the remaining cases. For a short ordering, list the offered orders and test each required relation. Use invented labels rather than assumptions about actual people. Try to find a counterexample before accepting a conclusion as necessary; if none remains, explain which rules excluded it.
Proofs verify this edition’s keys
The source checks enumerate finite Boolean worlds, allowed selections and ordering constraints independently of the runtime scorer. They confirm unique keys for these six tasks, not broad reasoning aptitude, cultural fairness or a hiring pass. No time pressure is measured. After seeing a proof, solving the same puzzle again may test recall; use a genuinely new example to practise the method.