Mensa Mensa IQ Deductive Reasoning Puzzles 2 — Questions and Answers
Question 1: All roses are flowers. Some flowers fade quickly. Therefore, which conclusion is valid?
- All roses fade quickly
- Some roses fade quickly
- No valid conclusion can be drawn (Correct answer)
- No flowers are roses
Correct answer: No valid conclusion can be drawn
The 'some flowers' that fade quickly may or may not include any roses, so nothing certain follows about roses.
Question 2: If no cats are dogs and all tigers are cats, what must be true?
- Some tigers are dogs
- No tigers are dogs (Correct answer)
- All dogs are tigers
- Some dogs are cats
Correct answer: No tigers are dogs
Since tigers fall entirely within cats and cats share nothing with dogs, tigers share nothing with dogs.
Question 3: Tom is taller than Sara. Sara is taller than Mike. Mike is taller than Joe. Who is shortest?
- Tom
- Sara
- Mike
- Joe (Correct answer)
Correct answer: Joe
The chain descends Tom > Sara > Mike > Joe, making Joe the shortest.
Question 4: Every member of the club pays dues. Raj does not pay dues. Therefore:
- Raj is a member
- Raj is not a member (Correct answer)
- Raj pays dues sometimes
- Some members skip dues
Correct answer: Raj is not a member
If all members pay dues and Raj does not, Raj cannot be a member.
Question 5: Some students are athletes. All athletes are healthy. Which follows?
- All students are healthy
- Some students are healthy (Correct answer)
- No students are healthy
- All healthy people are students
Correct answer: Some students are healthy
The students who are athletes must be healthy, so at least some students are healthy.
Question 6: If it rains, the match is cancelled. The match was not cancelled. What can be concluded?
- It rained
- It did not rain (Correct answer)
- It might have rained
- The match was postponed
Correct answer: It did not rain
By modus tollens, since rain guarantees cancellation and there was no cancellation, it did not rain.
Question 7: No reptiles are mammals. Some pets are reptiles. Therefore:
- All pets are mammals
- Some pets are not mammals (Correct answer)
- No pets are reptiles
- All reptiles are pets
Correct answer: Some pets are not mammals
The pets that are reptiles cannot be mammals, so some pets are not mammals.
Mensa Mensa IQ Deductive Reasoning Puzzles 2
All roses are flowers.
Some flowers fade quickly.
Therefore, which conclusion is valid?