Deductive Reasoning Flashcards

All board members voted on the resolution. Kevin did not vote on the resolution. What follows?

Answer: Kevin is not a board member

If all board members voted and Kevin did not vote, Kevin cannot be a board member.

Every student who scores above 90 earns an A. Lisa earned an A. What can be concluded?

Answer: Lisa may or may not have scored above 90

An A may be awarded for reasons beyond a score above 90, so Lisa's score cannot be confirmed.

No marketing emails are sent without approval. This email was sent. What must be true?

Answer: This email had approval

Since no unapproved emails are sent and this email was sent, it must have had approval.

All toxic chemicals require a warning label. Substance Z has no warning label. What can be deduced?

Answer: Substance Z is not toxic

By contrapositive, no warning label means it is not a toxic chemical.

Some engineers are also designers. All designers use CAD software. Which must be true?

Answer: Some engineers use CAD software

Engineers who are also designers must use CAD, so some engineers use CAD software.

If the alarm sounds, evacuate immediately. The alarm did NOT sound. What can be concluded?

Answer: Evacuation may or may not be needed

The alarm sounding is sufficient but not the only reason to evacuate — other factors could require it.

All completed orders are archived. Order #55 is not archived. What follows?

Answer: Order #55 is not complete

Contrapositive of 'completed → archived' is 'not archived → not complete.'