20+ Questions of Logical Deduction | Logical Reasoning   

Logical deduction questions are an important part of the Logical Reasoning section. Are you aware of the importance of being good at logical deduction? It’s a skill that comes in handy when you need to think critically and solve problems in daily life, such as when you have to make decisions or solve tricky puzzles. Logical deduction involves looking at the facts, finding patterns, and using them to draw logical conclusions.

Logical Deduction Problems are asked in exams, like

• UPSC CSE
• Defence Exams like ( AFCAT, NDA, CDS )
• State PSC Exams 
• Bank (PO & Clerk) Exams 
• SSC (CGL, 10+2, Steno, FCI, CPO, Multitasking)
• LIC (AAO & ADO)
• RRB

So, what are you waiting for? Start your preparation by solving these questions. In this blog, we will go over the fundamentals of logical deduction problems, as well as the types of questions asked in previous year exams and how to approach them. This will help you clear your basics and answer these logical deduction questions.

Must Read: Upcoming Government Exams 

What is Logical Deduction? What are Logical Deduction Problems? 

Logical deduction is the process of coming to a conclusion based on one or more statements, which are also called premises.

Two Inferential Processes of Deduction

Immediate Deductive Inference: In this case, the conclusion is inferred using any one of the three methods: conversion, obversion, or contraposition, from one of the given propositions.

1. Conversion: When you’re converting a statement, you flip the subject and predicate terms around. This means that the predicate term from the premise becomes the subject of the conclusion, and the subject from the premise becomes the predicate term. The result is known as the converse of the original proposition, which is the conclusion that you make from it.

2. Obversion: To modify a proposition’s quality, we can use a technique called obversion. Obversion involves replacing the predicate term with its complement.

3. Contraposition: To create the contrapositive of a statement, we can switch the subject and predicate terms and replace them with their complements.

Mediate Deductive Inference (SYLLOGISM): A syllogism, first presented by Aristotle, is a type of deductive argument in which a conclusion must be reached based on two statements, or premises.

Syllogism is concerned with three terms :

1. Major Term: Denoted by P (the initial letter of the word “Predicate”), it is the predicate of the conclusion.

2. Minor Term: Denoted by S (the initial letter of “Subject”), it is the topic of the conclusion. 

3. Middle Term: The term represented by M (the initial letter of “Middle”) is shared by both premises.

Also Read: 20+ Questions of Puzzles in Reasoning | Logical Reasoning

20 + Logical DeductionQuestions and Answers 

Below are two statements, followed by two conclusions. Assume both statements are true, even if they contradict common knowledge. Read the conclusions and choose which one logically follows from the two statements, ignoring common knowledge.

Answer: 

(A) If only conclusion I follows

(B) If only conclusion II follows

(C) If either I or II follows

(D) If neither I nor II follows and

(E) If both I and II follow.

Question 1

Statements: All students who study regularly pass exams. John studies regularly.

Conclusions:

John is a student.

John will pass exams.

A. Only conclusion I follows

B. Only conclusion II follows

C. Either I or II follows

D. Neither I nor II follows

E. Both I and II follow

Answer: Both I and II follow

Explanation: The first conclusion logically follows from the given premises because if all students who study regularly pass exams, and John studies regularly, then John must be a student. The second conclusion also follows logically because, according to the premises, if John is a student who studies regularly, he will pass exams.

Question 2

Statement: All windows are doors. No door is a wall

Conclusions:

1. No window is wall

2. No Wall is door

A) Only 1 follows

B) Only 2 follows

C) Either 1 or 2 follows

D) Both 1 and 2 follow

Answer: D) Both 1 and 2 follow

Explanation: Since both the premises are universal and one premise is negative, the conclusion must be universally negative. Also, the conclusion should not contain the middle term. So, 1 follows. However, 2 is the converse of the second premise, and thus it also holds.

Question 3

Statement: All dogs are mammals. Some mammals are cats.

Conclusions:

All dogs are cats.

Some cats are dogs.

A. Only conclusion I follow

B. Only conclusion II follows

C. Either I or II follows

D. Neither I nor II follows

E. Both I and II follow

Answer: Neither I nor II follows

Explanation: In this case, the premises establish that dogs are mammals, but they do not establish a direct relationship between dogs and cats. Therefore, neither of the conclusions can be logically deduced from the given premises.

Question 4

Statements: No women teacher can play. Some women teachers are athletes.

Conclusions:

Male athletes can play.

Some athletes can play.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option D

Explanation: Since one premise is negative, the conclusion must be negative. So, neither conclusion follows.

Question 5

Statements: All bags are cakes. All lamps are cakes.

Conclusions:

Some lamps are bags.

No lamp is a bag

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option C

Explanation: Since the middle term ‘cakes’ is not distributed even once in the premises, no definite conclusion follows. However, I and II involve only the extreme terms and form a complementary pair. So, either I or II follows.

Question 6

Statements: No bat is ball. No ball is wicket.

Conclusions:

No bat is wicket.

All wickets are bats.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option D

Explanation: Since both the premises are negative, no definite conclusion follows.

Question 7

Statements: All flowers are trees. No fruit is tree.

Conclusions:

No fruit is flower.

Some trees are flowers.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option E

Explanation: The conclusion must be universal negative and should not contain the middle term. So, it follows that ‘No flower is fruit’. I is the converse of this conclusion and thus it follows. II is the converse of the first premise and so it also holds.

Question 8

Statements: All roads are poles. No pole is a house.

Conclusions:

Some roads are houses.

Some houses are poles.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option D

Explanation: Since both the premises are universal and one premise is negative, the conclusion must be universal negative. So, neither I nor II follows.

Question 9

Statements: Every minister is a student. Every student is inexperienced.

Conclusions:

Every minister is inexperienced.

Some inexperienced are students.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option E

Explanation: ‘Every’ is equivalent to ‘All’. Thus, since both the premises are universal and affirmative, the conclusion must be universal and affirmative and should not contain the middle term. So, I follows. II is the converse of the second premise and thus it also holds.

Question 10

Statement: All fishes are grey in colour. Some fishes are heavy.

Conclusions:

All heavy fishes are grey in colour.

All light fishes are not grey in colour.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option A

Explanation: Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, it follows that ‘Some heavy things are grey in colour’. I is a cumulative result of this conclusion and the first premise. Thus, only I holds.

Question 11

Statement: All fish are tortoise. No tortoise is a crocodile.

Conclusions:

No crocodile is a fish.

No fish is a crocodile.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option E

Explanation: Since both the premises are universal and one premise is negative, the conclusion must be universal negative. Also, the conclusion should not contain the middle term. So, II follows; I is the converse of II and thus it also holds.

Question 12

Statement: Some swords are sharp. All swords are rusty

Conclusions:

Some rusty things are sharp.

Some rusty things are not sharp.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option A

Explanation: Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, I follows. Since both the premises are affirmative, the conclusion cannot be negative. Thus, II does not follow.

Question 13

Statement: Some papers are pens. Some pencils are pens.

Conclusions:

Some pens are pencils.

Some pens are papers.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option E

Explanation: Since both premises are particular, no definite conclusion follows. However, I is the converse of second premise, while II is the converse of the first premise. So, both of them hold.

Question 14

Statement: Many scooters are trucks. All trucks are trains.

Conclusions:

Some scooters are trains.

No truck is a scooter.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option A

Explanation: Since the first premise is particular, the conclusion must be particular and  should not contain the middle term. Thus, only I follows.

Question 15

Statements: All pens are chalks. All chairs are chalks.

Conclusions:

Some pens are chairs.

Some chalks are pens.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option B

Explanation: Since the middle term ‘chalks’ is not distributed even once in the premises, no definite conclusion follows. However, II is the converse of the first premise and so it holds.

Question 16

Statements: All men are married. Some men are educated.

Conclusions:

Some married are educated.

Some educated are married.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option E

Explanation: Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, I follows. II is the converse of I and thus it also holds.

Question 17

Statements: Some books are tables. Some tables are mirrors.

Conclusions:

Some mirrors are books.

No book is mirror.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option C

Explanation: Since both the premises are particular no definite conclusion follows. However, I and II involve only the extreme terms and form a complementary pair. Thus, either I or II follows.

Question 18

Statements: All men are dogs. All dogs are cats.

Conclusions:

All men are cats.

All cats are men.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option A

Explanation: Since both the premises are universal and affirmative, the conclusion must be universal affirmative. However, conclusion II, being an A-type proposition, distributes the term ‘cats’. Since the term ‘cats’ is distributed in II without being distributed in any of the premises, so conclusion II cannot follow. Thus, only I follows.

Question 19

Statements: Some pastries are toffees. All toffees are chocolates.

Conclusions:

Some chocolates are toffees.

Some toffees are not pastries.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option A

Explanation: Since one premise is particular, the conclusion must be particular and should not contain the middle term. Thus, it follows that ‘Some pastries are chocolates’, I is the converse of the second premise and so it holds. Since both the premises are affirmative, the conclusion cannot be negative. Thus, II does not follow.

Question 20

Statements: All artists are smokers. Some smokers are drunkards.

Conclusions:

All smokers are artists.

Some drunkards are not smokers.

1. Only conclusion I follows
2. Only conclusion II follows
3. Either I or II follows
4. Neither I nor II follows
5. Both I and II follow

Answer: Option D

Explanation: Since the middle term ‘smokers’ is not distributed even once in the premises, no definite conclusion follows.

Related Blogs

20 + Average Questions and Answers	20 + Simple Interest Questions and Answers
20 + Time and Work Questions and Answers	20 + Problems on Ages Questions and Answers
20 + Area and Perimeter Questions with Answers	20 + Profit and Loss Questions and Answers

This was all about the “Logical Deduction”.  For more such informative blogs, check out our Study Material Section, or you can learn more about us by visiting our  Indian exams page.