Question 1

Statements:
1. All teachers are educated.
2. Some educated people are doctors.

Conclusion: Some doctors are teachers.

Which of the following is true about this conclusion?

Accepted Answer

This is a classic syllogism testing whether students can identify invalid conclusions from valid premises. The two premises do not establish any direct relationship between doctors and teachers.

Question 2

Statements:
1. All teachers are educated.
2. Some educated people are doctors.

Conclusion: Some teachers are doctors.

Is the conclusion valid?

Accepted Answer

This is a classic partial syllogism trap. While all teachers are educated, and some educated people are doctors, we cannot conclude that some teachers are doctors because the 'some doctors' may come from the educated people who are NOT teachers.

Question 3

Statements:
1. All flowers are plants.
2. All plants need water.

Conclusion: All flowers need water.

Which of the following is true?

Accepted Answer

This is a straightforward valid syllogism using transitive logic: if A ⊆ B and B requires X, then A requires X.

Question 4

Statements:
1. All flowers are plants.
2. All plants need water.

Conclusion: All flowers need water.

Which statement best describes this conclusion?

Accepted Answer

This is a straightforward valid syllogism testing basic transitive reasoning. The conclusion logically follows from the premises.

Question 5

Statements:
1. No reptiles are mammals.
2. All snakes are reptiles.

Conclusion: No snakes are mammals.

Is the conclusion valid?

Accepted Answer

This is a valid syllogism using the rule: If A is a subset of B, and B has no overlap with C, then A has no overlap with C.

Question 6

Statements:
1. All doctors are professionals.
2. No professionals are unemployed.

Conclusion: Either all doctors are employed OR some doctors are unemployed.

Which statement is correct?

Accepted Answer

From the premises, we can definitively conclude that all doctors are employed (not the 'either/or'). The either/or conclusion presents two mutually exclusive options, but logic gives us one certain answer.

Question 7

Statements:
1. Some athletes are vegetarians.
2. All vegetarians are health-conscious.

Conclusion: Some athletes are health-conscious.

Is the conclusion valid?

Accepted Answer

This is a valid syllogism. The 'some athletes' who are vegetarians must also be health-conscious because all vegetarians are health-conscious.

Question 8

Statements:
1. No reptiles are mammals.
2. All snakes are reptiles.

Conclusion: No snakes are mammals.

Is this conclusion valid?

Accepted Answer

This syllogism tests understanding of negative premises and the proper application of the middle term in categorical logic.

Question 9

Statements:
1. Some athletes are tall.
2. All tall people are strong.

Conclusion: Either all athletes are strong, or no athletes are strong.

Which of the following is correct?

Accepted Answer

This question tests understanding of 'either/or' conclusions in syllogisms and whether students can recognize when such binary conclusions are unjustified.

Question 10

Statements:
1. No reptiles are mammals.
2. All snakes are reptiles.

Conclusion: No snakes are mammals.

Is the conclusion valid?

Accepted Answer

The conclusion IS valid. Since all snakes are reptiles (Premise 2) and no reptiles are mammals (Premise 1), it logically follows that no snakes can be mammals.

Question 11

Statements:
1. No politicians are saints.
2. All saints are honest.

Conclusion: Some politicians are not honest.

Is the conclusion valid?

Accepted Answer

The conclusion is NOT valid. From Premise 1, no politicians are saints. From Premise 2, all saints are honest. However, this does not tell us anything definitive about whether politicians are honest or not. A politician could be honest without being a saint. The premises do not provide enough information to conclude that some politicians are not honest.

Question 12

Statements:
1. Some athletes are disciplined.
2. All disciplined people are successful.

Conclusion: Some athletes are successful.

Is the conclusion valid?

Accepted Answer

The conclusion IS valid. From Premise 1, at least some athletes are disciplined. From Premise 2, all disciplined people (including those athletes) are successful. Therefore, at least some athletes must be successful.

Question 13

Statements:
1. All teachers are educated.
2. Some educated people are doctors.

Conclusion: Some doctors are teachers.

Is the conclusion valid?

Accepted Answer

The conclusion is NOT valid. From the given statements, we know all teachers are educated, and some educated people are doctors. However, this does not guarantee that any of those doctors are teachers. The educated doctors could be a completely different subset of educated people.

Question 14

Statements:
1. All teachers are educated.
2. Some educated people are doctors.

Conclusion: Some doctors are teachers.

Which of the following is true?

Accepted Answer

The conclusion does not logically follow from the given statements. While all teachers are educated and some educated people are doctors, we cannot conclude that some doctors are teachers because the educated people who are doctors may be a completely different group from teachers.

Question 15

Statements:
1. All fruits are healthy.
2. All apples are fruits.

Conclusion: All apples are healthy.

Which of the following is true?

Accepted Answer

The conclusion logically follows from the two premises. This is a classic valid syllogism using the transitive property: if all apples are fruits AND all fruits are healthy, then all apples must be healthy.

Question 16

Statements:
1. No criminals are honest.
2. All dishonest people are criminals.

Conclusion: All dishonest people are criminals.

Which of the following is true?

Accepted Answer

The conclusion is exactly the same as Premise 2, so it is definitely true. This tests whether students can identify when a conclusion directly restates a given premise.

Question 17

Statements:
1. Some students are athletes.
2. All athletes are disciplined.

Conclusion: Either some students are disciplined, or no students are disciplined.

Which of the following is true?

Accepted Answer

The conclusion is true. From the premises, we can derive that some students are athletes, and all athletes are disciplined, therefore some students are disciplined. The 'either/or' statement is satisfied because the first part ('some students are disciplined') is true.

Question 18

Statements:
1. No plants are animals.
2. All trees are plants.

Conclusion: No trees are animals.

Which of the following is true?

Accepted Answer

The conclusion is definitely true. Since all trees are plants, and no plants are animals, it logically follows that no trees are animals. This is a valid syllogism using the transitive property with negative statements.

Question 19

Statements:
1. All athletes are disciplined.
2. No lazy people are disciplined.
3. Some students are lazy.

Conclusion: Which of the following must be true?
(A) All students are athletes.
(B) Some students are not athletes.
(C) No students are athletes.
(D) Either all students are athletes or some students are not athletes.

Accepted Answer

From Statement 1: All athletes are disciplined (Athletes ⊆ Disciplined). From Statement 2: No lazy are disciplined (Lazy ∩ Disciplined = ∅). By contrapositive: All disciplined are not lazy (Disciplined ⊆ ¬Lazy), which means no disciplined people are lazy. From Statement 3: Some students are lazy. This means at least some students are NOT disciplined (since lazy people are not disciplined). Since athletes are disciplined, and some students are not disciplined, at least some students are NOT athletes. Option (B) is the correct conclusion. Option (D) is also technically a tautology, but (B) is the stronger, more specific valid conclusion that can be derived from the premises.

Question 20

Statements:
1. All philosophers are critical thinkers.
2. Some critical thinkers are not scientists.

Conclusion: Which of the following must be true?
(A) All philosophers are scientists.
(B) Some philosophers are not scientists.
(C) No philosophers are scientists.
(D) Either all philosophers are scientists or some philosophers are not scientists.

Accepted Answer

From Statement 1: All philosophers are critical thinkers (Philosophers ⊆ Critical thinkers). From Statement 2: Some critical thinkers are not scientists. However, this does NOT tell us whether the philosophers who are critical thinkers fall into the 'not scientists' category or not. The philosophers could be among the critical thinkers who ARE scientists, or among those who are NOT scientists. Therefore, we cannot definitively conclude (A), (B), or (C). Option (D) is a tautology—it must be true because either all philosophers are scientists OR at least one is not; there is no third option. This is the only logically necessary conclusion.

RBI Grade B Syllogism

Syllogism— Rules & Concept

Key Points to Remember

Exam-Specific Tips

Syllogism — Practice Questions

60-Second Revision — Syllogism