Each question below shows the correct answer with a full explanation. Use these to build conceptual understanding before attempting a timed quiz.
Logical Reasoning FundamentalsEasy
Q1. A=true, B=true. A AND B?
- A.True✓ Correct
- B.False
- C.Null
- D.Undefined
Explanation
AND: both true = true.
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Logical Reasoning FundamentalsEasy
Q2. NOT True?
- A.Error
- B.True
- C.False✓ Correct
- D.Null
Explanation
NOT inverts: True becomes False.
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Logical Reasoning FundamentalsEasy
Q3. A=true, B=false. A OR B?
- A.True✓ Correct
- B.Neither
- C.Undefined
- D.False
Explanation
OR: at least one true = true.
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Logical Reasoning FundamentalsEasy
Q4. General to specific reasoning?
- A.Abductive
- B.Inductive
- C.Analogical
- D.Deductive✓ Correct
Explanation
Deductive: general to specific.
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Logical Reasoning FundamentalsEasy
Q5. Specific to general reasoning?
- A.Deductive
- B.Abductive
- C.Inductive✓ Correct
- D.Circular
Explanation
Inductive: specific to general.
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Logical Reasoning FundamentalsEasy
Q6. Truth table with 2 variables has how many rows?
- A.16
- B.4✓ Correct
- C.2
- D.8
Explanation
4 is the correct answer to this question.
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Logical Reasoning FundamentalsEasy
Q7. What is a logical fallacy?
- A.A correct logical argument
- B.An error making argument invalid✓ Correct
- C.A type of search algorithm
- D.A specific data structure
Explanation
Error that renders argument invalid.
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Logical Reasoning FundamentalsEasy
Q8. All cats are animals. Tom is a cat. Therefore?
- A.Tom is actually a dog
- B.Nothing can be concluded
- C.Tom is not an animal
- D.Tom is an animal too✓ Correct
Explanation
Classic syllogism: Tom must be an animal.
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Logical Reasoning FundamentalsEasy
Q9. What does XOR return?
- A.Always returns true as output
- B.True when exactly one is true✓ Correct
- C.Always returns false as output
- D.True when both inputs are true
Explanation
XOR: exactly one true.
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Logical Reasoning FundamentalsEasy
Q10. What is a premise?
- A.A conclusion drawn from evidence
- B.A statement assumed true for reasoning✓ Correct
- C.A question posed to the audience
- D.An error found in the argument
Explanation
Foundation for logical conclusions.
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Logical Reasoning FundamentalsMedium
Q11. Contrapositive of If P then Q?
- A.If P then not Q
- B.If not Q then not P✓ Correct
- C.If Q then P
- D.If not P then not Q
Explanation
Contrapositive is logically equivalent.
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Logical Reasoning FundamentalsMedium
Q12. Which is De Morgan's Law?
- A.NOT A = A
- B.NOT(A AND B) = NOT A OR NOT B✓ Correct
- C.A AND B = A OR B
- D.A XOR B = A AND B
Explanation
NOT(A AND B) = (NOT A) OR (NOT B).
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Logical Reasoning FundamentalsMedium
Q13. What is modus ponens?
- A.P->Q, P false, therefore Q false
- B.P->Q, Q false, therefore P false
- C.P->Q, Q true, therefore P
- D.P->Q, P true, therefore Q✓ Correct
Explanation
If P then Q; P true; Q must be true.
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Logical Reasoning FundamentalsMedium
Q14. What is modus tollens?
- A.P->Q, P true, therefore Q
- B.P->Q, Q true, therefore P
- C.P->Q, Q false, therefore P false✓ Correct
- D.P->Q, P false, therefore Q false
Explanation
If P then Q; Q false; P must be false.
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Logical Reasoning FundamentalsMedium
Q15. Truth table with 4 variables?
- A.16 rows✓ Correct
- B.32 rows
- C.8 rows
- D.4 rows
Explanation
16 rows is the correct answer to this question.
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Logical Reasoning FundamentalsMedium
Q16. What is a tautology?
- A.Always true regardless of values✓ Correct
- B.A logical contradiction in reasoning
- C.A statement that is always false
- D.A statement that is sometimes true
Explanation
True under every interpretation.
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Logical Reasoning FundamentalsMedium
Q17. What is a contradiction?
- A.Always false regardless of values✓ Correct
- B.A tautology under all conditions
- C.A valid argument with true premises
- D.A statement that is always true
Explanation
False under every interpretation.
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Logical Reasoning FundamentalsMedium
Q18. What does P <-> Q mean?
- A.P implies Q in one direction only
- B.P is true if and only if Q is true✓ Correct
- C.Q implies P in one direction only
- D.Both P and Q are always true together
Explanation
Biconditional: same truth value.
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Logical Reasoning FundamentalsMedium
Q19. What is proof by contradiction?
- A.A type of mathematical induction
- B.Proving the statement is false
- C.A direct proof from axioms
- D.Assume opposite, show contradiction✓ Correct
Explanation
Assumes negation, derives contradiction.
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Logical Reasoning FundamentalsMedium
Q20. Affirming the consequent fallacy?
- A.Rain->wet. No rain. Not wet.
- B.Rain->wet. Dry. No rain.
- C.Rain->wet. Wet. Therefore rained.✓ Correct
- D.Rain->wet. Rained. Wet.
Explanation
Ground could be wet for other reasons.
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Logical Reasoning FundamentalsHard
Q21. Universal quantifier means?
- A.For exactly one element only
- B.For all elements in the domain✓ Correct
- C.For no elements in the domain
- D.There exists at least one element
Explanation
For all elements in the domain.
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Logical Reasoning FundamentalsHard
Q22. Negation of forall x P(x)?
- A.exists x NOT P(x)✓ Correct
- B.forall x NOT P(x)
- C.NOT exists x P(x)
- D.forall x P(x) still
Explanation
Not all = there exists one that is not.
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Logical Reasoning FundamentalsHard
Q23. What is mathematical induction?
- A.Proving base case plus if n then n+1✓ Correct
- B.Testing all possible cases manually
- C.Guessing the answer to the problem
- D.Only proving the base case alone
Explanation
Base case plus inductive step.
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Logical Reasoning FundamentalsHard
Q24. What is a clause in resolution?
- A.A disjunction of logical literals✓ Correct
- B.A conjunction of several functions
- C.A complete executable program
- D.A variable assignment statement
Explanation
Clause = disjunction (OR) of literals.
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Logical Reasoning FundamentalsHard
Q25. Logical completeness means?
- A.The system runs very fast
- B.The system has no bugs at all
- C.Every valid formula is provable✓ Correct
- D.It uses all logical operators
Explanation
Every valid formula is derivable.
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Logical Reasoning FundamentalsHard
Q26. Godel's first incompleteness theorem?
- A.All formal systems are complete
- B.All true statements are provable
- C.Consistent systems have unprovable truths✓ Correct
- D.Logic is unnecessary for proofs
Explanation
Sufficiently powerful systems have unprovable truths.
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Logical Reasoning FundamentalsHard
Q27. What is satisfiability (SAT)?
- A.Whether an assignment makes it true✓ Correct
- B.A formula that is always true
- C.A formula with no variable bindings
- D.A formula that is always false
Explanation
First proven NP-complete problem.
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Logical Reasoning FundamentalsHard
Q28. What is soundness?
- A.It uses auditory signal processing
- B.The system proves everything possible
- C.The system has zero error states
- D.Every provable statement is valid✓ Correct
Explanation
Only true statements can be proven.
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Logical Reasoning FundamentalsHard
Q29. SAT worst case?
- A.O(n^2) quadratic time
- B.O(n) linear time
- C.Exponential (NP-complete)✓ Correct
- D.O(n log n) linearithmic
Explanation
NP-complete: exponential worst case.
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Logical Reasoning FundamentalsHard
Q30. What is semantic entailment?
- A.A programming concept for objects
- B.A specific data type for storage
- C.A syntax rule in formal languages
- D.Premises true implies conclusion true✓ Correct
Explanation
Truth of premises guarantees truth of conclusion.
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