Syllogism
All cats are animals. Some animals are pets. Which of the following conclusions is definitely true?
A
All cats are pets
B
Some cats are pets
C
No cat is a pet
D
All animals are cats
Correct Answer:
B. Some cats are pets
Explanation:
From 'All cats are animals' and 'Some animals are pets', we can only conclude that it's possible some cats are pets, but not definite.
No flower is a fruit. All fruits are sweet. What can be concluded?
A
Some flowers are sweet
B
No flower is sweet
C
All flowers are sweet
D
All sweet things are fruits
Correct Answer:
B. No flower is sweet
Explanation:
Since no flower is a fruit, and all fruits are sweet, flowers cannot be sweet through this relation.
All doctors are professionals. All professionals are educated. Therefore, which conclusion follows?
A
All educated people are doctors
B
Some professionals are not educated
C
All doctors are educated
D
No doctor is educated
Correct Answer:
C. All doctors are educated
Explanation:
By transitive property: All doctors are professionals, and all professionals are educated, therefore all doctors are educated.
Some books are novels. All novels are stories. Can we conclude 'Some books are stories'?
A
Yes, definitely
B
No, it's uncertain
C
No, it's false
D
Cannot be determined
Correct Answer:
A. Yes, definitely
Explanation:
Some books are novels, and all novels are stories, therefore some books must be stories by logical deduction.
All trees are plants. No animal is a plant. Which of the following is true?
A
All animals are trees
B
No animal is a tree
C
Some animals are trees
D
All trees are animals
Correct Answer:
B. No animal is a tree
Explanation:
Since all trees are plants and no animal is a plant, logically no animal can be a tree.
Some singers are dancers. Some dancers are actors. Which conclusion is definitely correct?
A
Some singers are actors
B
All singers are actors
C
Some singers may or may not be actors
D
No singer is an actor
Correct Answer:
C. Some singers may or may not be actors
Explanation:
From two 'some' statements, we cannot draw a definite conclusion about the relationship between singers and actors.
All gold is precious. Some precious things are expensive. Can we say 'Some gold is expensive'?
A
Yes, definitely
B
No, it's uncertain
C
No, it's impossible
D
Only some gold is precious
Correct Answer:
B. No, it's uncertain
Explanation:
Although all gold is precious, only some precious things are expensive, so we cannot definitively conclude gold is expensive.
No criminal is honest. Some dishonest people are criminals. What follows?
A
All dishonest people are criminals
B
Some dishonest people are not criminals
C
All criminals are dishonest
D
No dishonest person is honest
Correct Answer:
C. All criminals are dishonest
Explanation:
Since no criminal is honest, it means all criminals must be dishonest (contrapositive of the first statement).
All leaders are decision makers. Some decision makers are not politicians. Which conclusion is valid?
A
Some leaders are not politicians
B
All leaders are politicians
C
Some politicians are decision makers
D
All decision makers are leaders
Correct Answer:
A. Some leaders are not politicians
Explanation:
Since some decision makers are not politicians, and all leaders are decision makers, some leaders must not be politicians.
No student is lazy. All lazy people are unsuccessful. What can be concluded?
A
No student is unsuccessful
B
All students are successful
C
Some students are unsuccessful
D
The conclusion cannot be determined
Correct Answer:
D. The conclusion cannot be determined
Explanation:
While no student is lazy, and lazy people are unsuccessful, this doesn't tell us about unsuccessful students who might be lazy or for other reasons.
