Mathematical Reasoning — One Question at a Time
Practise 176 Mathematical Reasoning multiple-choice questions covering sets, propositional logic, inference rules, quantifiers, relations, functions and sequences. Work through one question at a time, check the correct answer with an explanation, and select Next Question to continue. This is self-paced practice without automatic scoring.
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Question 1. If A has 3 distinct elements, how many subsets does A have?
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Correct answer: A. 8
Each element is either included or excluded, giving 2^3 = 8 subsets.
Question 2. How many proper subsets does a 3-element set have?
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Correct answer: D. 7
There are 2^3 subsets; exclude the set itself.
Question 3. What is the cardinality of the power set of a set with 2 elements?
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Correct answer: C. 4
The power set contains all 2^2 subsets.
Question 4. If A has 4 distinct elements, how many subsets does A have?
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Correct answer: C. 16
Each element is either included or excluded, giving 2^4 = 16 subsets.
Question 5. How many proper subsets does a 4-element set have?
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Correct answer: B. 15
There are 2^4 subsets; exclude the set itself.
Question 6. What is the cardinality of the power set of a set with 3 elements?
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Correct answer: A. 8
The power set contains all 2^3 subsets.
Question 7. If A has 5 distinct elements, how many subsets does A have?
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Correct answer: A. 32
Each element is either included or excluded, giving 2^5 = 32 subsets.
Question 8. How many proper subsets does a 5-element set have?
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Correct answer: D. 31
There are 2^5 subsets; exclude the set itself.
Question 9. What is the cardinality of the power set of a set with 4 elements?
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Correct answer: C. 16
The power set contains all 2^4 subsets.
Question 10. If A has 6 distinct elements, how many subsets does A have?
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Correct answer: C. 64
Each element is either included or excluded, giving 2^6 = 64 subsets.
Question 11. How many proper subsets does a 6-element set have?
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Correct answer: B. 63
There are 2^6 subsets; exclude the set itself.
Question 12. What is the cardinality of the power set of a set with 5 elements?
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Correct answer: A. 32
The power set contains all 2^5 subsets.
Question 13. If A has 7 distinct elements, how many subsets does A have?
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Correct answer: A. 128
Each element is either included or excluded, giving 2^7 = 128 subsets.
Question 14. How many proper subsets does a 7-element set have?
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Correct answer: D. 127
There are 2^7 subsets; exclude the set itself.
Question 15. What is the cardinality of the power set of a set with 6 elements?
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Correct answer: C. 64
The power set contains all 2^6 subsets.
Question 16. If A has 8 distinct elements, how many subsets does A have?
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Correct answer: C. 256
Each element is either included or excluded, giving 2^8 = 256 subsets.
Question 17. How many proper subsets does a 8-element set have?
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Correct answer: B. 255
There are 2^8 subsets; exclude the set itself.
Question 18. What is the cardinality of the power set of a set with 7 elements?
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Correct answer: A. 128
The power set contains all 2^7 subsets.
Question 19. If A has 9 distinct elements, how many subsets does A have?
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Correct answer: A. 512
Each element is either included or excluded, giving 2^9 = 512 subsets.
Question 20. How many proper subsets does a 9-element set have?
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Correct answer: D. 511
There are 2^9 subsets; exclude the set itself.
Question 21. What is the cardinality of the power set of a set with 8 elements?
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Correct answer: C. 256
The power set contains all 2^8 subsets.
Question 22. If A has 10 distinct elements, how many subsets does A have?
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Correct answer: C. 1024
Each element is either included or excluded, giving 2^10 = 1024 subsets.
Question 23. How many proper subsets does a 10-element set have?
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Correct answer: B. 1023
There are 2^10 subsets; exclude the set itself.
Question 24. What is the cardinality of the power set of a set with 9 elements?
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Correct answer: A. 512
The power set contains all 2^9 subsets.
Question 25. If |A|=10, |B|=8, and |A∩B|=3, find |A∪B|.
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Correct answer: B. 15
Inclusion–exclusion: |A∪B| = 10+8−3 = 15.
Question 26. In a universal set of 24 elements, A has 11 elements. Find |Aᶜ|.
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Correct answer: A. 13
The complement contains 24−11 = 13 elements.
Question 27. If |A|=9, |B|=7, and |A∩B|=2, how many elements belong to A only?
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Correct answer: D. 7
A only means |A\B| = |A|−|A∩B| = 7.
Question 28. Which expression is equal to (A∪B)ᶜ (De Morgan’s law), for arbitrary sets A and B?
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Correct answer: C. Aᶜ∩Bᶜ
Complement of a union is the intersection of the complements.
Question 29. Which identity holds for any set A and any universe U?
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Correct answer: B. A∪Aᶜ = U
Every element of U lies either in A or in its complement.
Question 30. If |A|=11, |B|=9, and |A∩B|=4, find |A∪B|.
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Correct answer: D. 16
Inclusion–exclusion: |A∪B| = 11+9−4 = 16.
Question 31. In a universal set of 25 elements, A has 12 elements. Find |Aᶜ|.
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Correct answer: C. 13
The complement contains 25−12 = 13 elements.
Question 32. If |A|=10, |B|=8, and |A∩B|=2, how many elements belong to A only?
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Correct answer: B. 8
A only means |A\B| = |A|−|A∩B| = 8.
Question 33. If A={1,2,3,4} and B={3,4,5}, what is A\B?
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Correct answer: A. {1,2}
A\B contains elements of A not in B.
Question 34. If A={1,2,3} and B={3,4}, what is the symmetric difference A△B?
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Correct answer: B. {1,2,4}
Symmetric difference contains elements belonging to exactly one of the sets.
Question 35. If |A|=12, |B|=10, and |A∩B|=5, find |A∪B|.
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Correct answer: B. 17
Inclusion–exclusion: |A∪B| = 12+10−5 = 17.
Question 36. In a universal set of 26 elements, A has 13 elements. Find |Aᶜ|.
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Correct answer: A. 13
The complement contains 26−13 = 13 elements.
Question 37. If |A|=11, |B|=9, and |A∩B|=2, how many elements belong to A only?
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Correct answer: D. 9
A only means |A\B| = |A|−|A∩B| = 9.
Question 38. If |A|=3 and |B|=4, how many ordered pairs are in A×B?
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Correct answer: B. 12
The Cartesian product contains |A||B|=3×4=12 ordered pairs.
Question 39. If A⊆B and B⊆A, which conclusion follows?
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Correct answer: B. A=B
Mutual inclusion is the defining criterion for equality of sets.
Question 40. If |A|=13, |B|=11, and |A∩B|=6, find |A∪B|.
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Correct answer: D. 18
Inclusion–exclusion: |A∪B| = 13+11−6 = 18.
Question 41. In a universal set of 27 elements, A has 14 elements. Find |Aᶜ|.
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Correct answer: C. 13
The complement contains 27−14 = 13 elements.
Question 42. If |A|=12, |B|=10, and |A∩B|=2, how many elements belong to A only?
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Correct answer: B. 10
A only means |A\B| = |A|−|A∩B| = 10.
Question 43. For arbitrary sets A and B, what is A∩(A∪B)?
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Correct answer: C. A
The absorption law gives A∩(A∪B)=A.
Question 44. For arbitrary sets A and B, what is A∪(A∩B)?
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Correct answer: A. A
The absorption law gives A∪(A∩B)=A.
Question 45. If |A|=14, |B|=12, and |A∩B|=7, find |A∪B|.
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Correct answer: B. 19
Inclusion–exclusion: |A∪B| = 14+12−7 = 19.
Question 46. In a universal set of 28 elements, A has 15 elements. Find |Aᶜ|.
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Correct answer: A. 13
The complement contains 28−15 = 13 elements.
Question 47. If |A|=13, |B|=11, and |A∩B|=2, how many elements belong to A only?
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Correct answer: D. 11
A only means |A\B| = |A|−|A∩B| = 11.
Question 48. Which identity is the distributive law of intersection over union?
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Correct answer: A. A∩(B∪C)=(A∩B)∪(A∩C)
Intersection distributes over union.
Question 49. Which expression equals (A∩B)ᶜ for sets in a fixed universe?
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Correct answer: C. Aᶜ∪Bᶜ
By De Morgan’s second law, the complement of an intersection is the union of complements.
Question 50. If |A|=15, |B|=13, and |A∩B|=8, find |A∪B|.
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Correct answer: D. 20
Inclusion–exclusion: |A∪B| = 15+13−8 = 20.
Question 51. In a universal set of 29 elements, A has 16 elements. Find |Aᶜ|.
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Correct answer: C. 13
The complement contains 29−16 = 13 elements.
Question 52. If |A|=14, |B|=12, and |A∩B|=2, how many elements belong to A only?
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Correct answer: B. 12
A only means |A\B| = |A|−|A∩B| = 12.
Question 53. If A and B are disjoint, |A|=6 and |B|=5, find |A∪B|.
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Correct answer: C. 11
Disjoint sets have empty intersection, so |A∪B|=6+5=11.
Question 54. If A={a,b,c}, how many subsets contain a?
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Correct answer: B. 4
Fix a as included, then independently choose whether to include b and c: 2²=4.
Question 55. If |A|=16, |B|=14, and |A∩B|=9, find |A∪B|.
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Correct answer: B. 21
Inclusion–exclusion: |A∪B| = 16+14−9 = 21.
Question 56. In a universal set of 30 elements, A has 17 elements. Find |Aᶜ|.
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Correct answer: A. 13
The complement contains 30−17 = 13 elements.
Question 57. If |A|=15, |B|=13, and |A∩B|=2, how many elements belong to A only?
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Correct answer: D. 13
A only means |A\B| = |A|−|A∩B| = 13.
Question 58. For any set A, which statement about A∩∅ is true?
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Correct answer: C. A∩∅=∅
No element belongs to the empty set, so its intersection with any set is empty.
Question 59. If |A∪B|=18, |A|=12 and |B|=10, find |A∩B|.
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Correct answer: A. 4
Rearrange inclusion-exclusion: |A∩B|=12+10−18=4.
Question 60. If |A|=17, |B|=15, and |A∩B|=10, find |A∪B|.
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Correct answer: D. 22
Inclusion–exclusion: |A∪B| = 17+15−10 = 22.
Question 61. In a universal set of 31 elements, A has 18 elements. Find |Aᶜ|.
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Correct answer: C. 13
The complement contains 31−18 = 13 elements.
Question 62. If |A|=16, |B|=14, and |A∩B|=2, how many elements belong to A only?
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Correct answer: B. 14
A only means |A\B| = |A|−|A∩B| = 14.
Question 63. If A={2,4,6} and B={1,2,3}, what is A∩B?
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Correct answer: B. {2}
Only the element 2 is common to both sets.
Question 64. If A has five elements, how many 2-element subsets does it have?
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Correct answer: C. 10
Choose any two of five elements: C(5,2)=10.
Question 65. Let p be true and q be true. What is p ∧ q?
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Correct answer: A. True
A conjunction is true only when both component propositions are true.
Question 66. Let p be true and q be true. What is p ∨ q (inclusive OR)?
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Correct answer: D. True
Inclusive OR is false only if both propositions are false.
Question 67. Which is the contrapositive of "If an integer n is divisible by 2, then n has property P"?
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Correct answer: A. If n does not have property P, then n is not divisible by 2.
The contrapositive of p→q is ¬q→¬p.
Question 68. Let p be false and q be false. What is p ∧ q?
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Correct answer: C. False
A conjunction is true only when both component propositions are true.
Question 69. Let p be false and q be false. What is p ∨ q (inclusive OR)?
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Correct answer: B. False
Inclusive OR is false only if both propositions are false.
Question 70. Which is the contrapositive of "If an integer n is divisible by 3, then n has property P"?
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Correct answer: C. If n does not have property P, then n is not divisible by 3.
The contrapositive of p→q is ¬q→¬p.
Question 71. Let p be true and q be false. What is p ∧ q?
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Correct answer: A. False
A conjunction is true only when both component propositions are true.
Question 72. Let p be true and q be false. What is p ∨ q (inclusive OR)?
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Correct answer: D. True
Inclusive OR is false only if both propositions are false.
Question 73. Which is the contrapositive of "If an integer n is divisible by 4, then n has property P"?
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Correct answer: A. If n does not have property P, then n is not divisible by 4.
The contrapositive of p→q is ¬q→¬p.
Question 74. Let p be false and q be true. What is p ∧ q?
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Correct answer: C. False
A conjunction is true only when both component propositions are true.
Question 75. Let p be false and q be true. What is p ∨ q (inclusive OR)?
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Correct answer: B. True
Inclusive OR is false only if both propositions are false.
Question 76. Which is the contrapositive of "If an integer n is divisible by 5, then n has property P"?
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Correct answer: C. If n does not have property P, then n is not divisible by 5.
The contrapositive of p→q is ¬q→¬p.
Question 77. If p is true and q is false, what is the truth value of p ⊕ q (exclusive OR)?
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Correct answer: A. True
Exclusive OR is true when exactly one proposition is true.
Question 78. If p is true and q is true, what is ¬(p∧q)?
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Correct answer: B. False
Both propositions are true, so their conjunction is true and its negation is false.
Question 79. Which is the contrapositive of "If an integer n is divisible by 6, then n has property P"?
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Correct answer: A. If n does not have property P, then n is not divisible by 6.
The contrapositive of p→q is ¬q→¬p.
Question 80. If p is false and q is true, what is ¬p∧q?
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Correct answer: C. True
Since p is false, ¬p is true, and q is true.
Question 81. If p is false and q is false, what is ¬(p∨q)?
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Correct answer: B. True
The disjunction is false, so its negation is true.
Question 82. Which is the contrapositive of "If an integer n is divisible by 7, then n has property P"?
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Correct answer: C. If n does not have property P, then n is not divisible by 7.
The contrapositive of p→q is ¬q→¬p.
Question 83. For p=true and q=false, evaluate ¬p∨q.
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Correct answer: B. False
Both ¬p and q are false, making their disjunction false.
Question 84. For p=false and q=true, evaluate p∧¬q.
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Correct answer: B. False
Both p and ¬q are false, so their conjunction is false.
Question 85. Which is the contrapositive of "If an integer n is divisible by 8, then n has property P"?
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Correct answer: A. If n does not have property P, then n is not divisible by 8.
The contrapositive of p→q is ¬q→¬p.
Question 86. For p=true and q=true, evaluate (p∨q)∧¬q.
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Correct answer: B. False
The disjunction is true but ¬q is false, so the conjunction is false.
Question 87. For p=false and q=false, evaluate ¬p∨¬q.
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Correct answer: C. True
Both negations are true, hence their disjunction is true.
Question 88. Which is the contrapositive of "If an integer n is divisible by 9, then n has property P"?
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Correct answer: C. If n does not have property P, then n is not divisible by 9.
The contrapositive of p→q is ¬q→¬p.
Question 89. If p is true and q is true, what is the truth value of p → q?
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Correct answer: C. True
A conditional is false only when its antecedent is true and its consequent false.
Question 90. If p is false and q is false, what is the truth value of p → q?
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Correct answer: A. True
A conditional is false only when its antecedent is true and its consequent false.
Question 91. If p is true and q is false, what is the truth value of p → q?
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Correct answer: C. False
A conditional is false only when its antecedent is true and its consequent false.
Question 92. If p is false and q is true, what is the truth value of p → q?
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Correct answer: A. True
A conditional is false only when its antecedent is true and its consequent false.
Question 93. For p=true and q=false, what is the truth value of q→p?
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Correct answer: B. True
A conditional with a false antecedent is true.
Question 94. For p=false and q=true, what is p→¬q?
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Correct answer: B. True
The antecedent p is false, so the implication is true.
Question 95. For p=true and q=true, what is ¬p→q?
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Correct answer: B. True
The antecedent ¬p is false, hence the conditional is true.
Question 96. For p=false and q=false, evaluate ¬p→q.
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Correct answer: B. False
Here ¬p is true and q is false, so the implication is false.
Question 97. If p is true and q is true, evaluate p ↔ q.
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Correct answer: B. True
A biconditional is true exactly when the two truth values match.
Question 98. If p is false and q is false, evaluate p ↔ q.
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Correct answer: D. True
A biconditional is true exactly when the two truth values match.
Question 99. If p is true and q is false, evaluate p ↔ q.
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Correct answer: B. False
A biconditional is true exactly when the two truth values match.
Question 100. If p is false and q is true, evaluate p ↔ q.
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Correct answer: D. False
A biconditional is true exactly when the two truth values match.
Question 101. For p=true and q=false, what is p↔¬q?
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Correct answer: A. True
Both p and ¬q are true, making the biconditional true.
Question 102. For p=false and q=true, what is ¬p↔q?
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Correct answer: B. True
Both ¬p and q are true, so the biconditional is true.
Question 103. For p=true and q=true, evaluate p↔¬q.
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Correct answer: C. False
p is true but ¬q is false, so the biconditional is false.
Question 104. For p=false and q=false, evaluate ¬p↔q.
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Correct answer: B. False
¬p is true while q is false, so the biconditional is false.
Question 105. For a proposition p, which expression is always true?
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Correct answer: D. p ∨ ¬p
By the law of excluded middle, p∨¬p is a tautology.
Question 106. For a proposition p about a number, which expression is always true?
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Correct answer: B. p ∨ ¬p
By the law of excluded middle, p∨¬p is a tautology.
Question 107. Which proposition is logically equivalent to ¬(p∧q)?
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Correct answer: B. ¬p∨¬q
De Morgan’s law states ¬(p∧q) ≡ ¬p∨¬q.
Question 108. Which expression is logically equivalent to p→q?
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Correct answer: C. ¬p∨q
A material implication is equivalent to ¬p∨q.
Question 109. Which proposition is a contradiction for every p?
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Correct answer: C. p∧¬p
A proposition cannot be true and false simultaneously.
Question 110. Which expression is equivalent to ¬¬p in classical logic?
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Correct answer: A. p
The double-negation law states ¬¬p ≡ p.
Question 111. Which expression is equivalent to p∧(p∨q)?
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Correct answer: B. p
The absorption law reduces p∧(p∨q) to p.
Question 112. Which expression is equivalent to ¬(p∨q)?
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Correct answer: C. ¬p∧¬q
De Morgan’s law gives ¬(p∨q) ≡ ¬p∧¬q.
Question 113. Which inference rule justifies: "p→q; p; therefore q" (example 1)?
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Correct answer: C. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 114. Which inference rule justifies: "p→q; p; therefore q" (example 2)?
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Correct answer: A. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 115. Which inference rule justifies: "p→q; p; therefore q" (example 3)?
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Correct answer: C. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 116. Which inference rule justifies: "p→q; p; therefore q" (example 4)?
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Correct answer: A. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 117. Which inference rule justifies: "p→q; p; therefore q" (example 5)?
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Correct answer: C. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 118. Which inference rule justifies: "p→q; p; therefore q" (example 6)?
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Correct answer: A. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 119. Which inference rule justifies: "p→q; p; therefore q" (example 7)?
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Correct answer: C. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 120. Which inference rule justifies: "p→q; p; therefore q" (example 8)?
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Correct answer: A. Modus ponens
Modus ponens applies the conditional after establishing its antecedent.
Question 121. What is the negation of "Every element of the set {1,2,…,3} has property P"?
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Correct answer: B. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 122. Negate the statement "There exists an integer x such that x>5 and P(x)."
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Correct answer: A. For every integer x, x≤5 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 123. What is the negation of "Every element of the set {1,2,…,4} has property P"?
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Correct answer: D. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 124. Negate the statement "There exists an integer x such that x>6 and P(x)."
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Correct answer: C. For every integer x, x≤6 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 125. What is the negation of "Every element of the set {1,2,…,5} has property P"?
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Correct answer: B. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 126. Negate the statement "There exists an integer x such that x>7 and P(x)."
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Correct answer: A. For every integer x, x≤7 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 127. What is the negation of "Every element of the set {1,2,…,6} has property P"?
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Correct answer: D. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 128. Negate the statement "There exists an integer x such that x>8 and P(x)."
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Correct answer: C. For every integer x, x≤8 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 129. What is the negation of "Every element of the set {1,2,…,7} has property P"?
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Correct answer: B. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 130. Negate the statement "There exists an integer x such that x>9 and P(x)."
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Correct answer: A. For every integer x, x≤9 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 131. What is the negation of "Every element of the set {1,2,…,8} has property P"?
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Correct answer: D. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 132. Negate the statement "There exists an integer x such that x>10 and P(x)."
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Correct answer: C. For every integer x, x≤10 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 133. What is the negation of "Every element of the set {1,2,…,9} has property P"?
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Correct answer: B. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 134. Negate the statement "There exists an integer x such that x>11 and P(x)."
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Correct answer: A. For every integer x, x≤11 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 135. What is the negation of "Every element of the set {1,2,…,10} has property P"?
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Correct answer: D. There exists an element in the set without property P.
Negating ∀x P(x) gives ∃x ¬P(x).
Question 136. Negate the statement "There exists an integer x such that x>12 and P(x)."
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Correct answer: C. For every integer x, x≤12 or not P(x).
Negating an existential quantifier makes it universal, and ¬(A∧B) = ¬A∨¬B.
Question 137. On the integers, consider aRb iff a−b is divisible by 2. Which description is correct?
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Correct answer: D. R is an equivalence relation
Congruence modulo 2 is reflexive, symmetric and transitive.
Question 138. On the integers, consider aRb iff a−b is divisible by 3. Which description is correct?
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Correct answer: B. R is an equivalence relation
Congruence modulo 3 is reflexive, symmetric and transitive.
Question 139. On the integers, consider aRb iff a−b is divisible by 4. Which description is correct?
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Correct answer: D. R is an equivalence relation
Congruence modulo 4 is reflexive, symmetric and transitive.
Question 140. On the integers, consider aRb iff a−b is divisible by 5. Which description is correct?
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Correct answer: B. R is an equivalence relation
Congruence modulo 5 is reflexive, symmetric and transitive.
Question 141. On the integers, consider aRb iff a−b is divisible by 6. Which description is correct?
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Correct answer: D. R is an equivalence relation
Congruence modulo 6 is reflexive, symmetric and transitive.
Question 142. On the integers, consider aRb iff a−b is divisible by 7. Which description is correct?
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Correct answer: B. R is an equivalence relation
Congruence modulo 7 is reflexive, symmetric and transitive.
Question 143. On the integers, consider aRb iff a−b is divisible by 8. Which description is correct?
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Correct answer: D. R is an equivalence relation
Congruence modulo 8 is reflexive, symmetric and transitive.
Question 144. On the integers, consider aRb iff a−b is divisible by 9. Which description is correct?
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Correct answer: B. R is an equivalence relation
Congruence modulo 9 is reflexive, symmetric and transitive.
Question 145. On the set of integers, which relation is a partial order?
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Correct answer: C. a≤b
The usual ≤ relation is reflexive, antisymmetric and transitive.
Question 146. On positive integers, which relation defines a partial order?
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Correct answer: A. a divides b
Divisibility is reflexive, antisymmetric and transitive on positive integers.
Question 147. On the power set P({1,2}), which relation is a partial order?
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Correct answer: B. A⊆B
Set inclusion is reflexive, antisymmetric and transitive.
Question 148. Which property fails for the usual strict order < on integers when viewed as a partial order?
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Correct answer: C. Reflexivity
Question 149. For the usual ≤ on integers, which is true of 3 and 5?
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Correct answer: B. 3≤5
Three is less than five, so 3≤5.
Question 150. Under divisibility on positive integers, is 2 comparable with 3?
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Correct answer: C. No, neither divides the other
Neither 2 divides 3 nor 3 divides 2.
Question 151. Which relation on integers is an equivalence relation but not a partial order?
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Correct answer: C. a−b is even
Congruence modulo 2 is an equivalence relation, but distinct same-parity integers violate antisymmetry.
Question 152. In a partially ordered set, what does a≤b and b≤a imply?
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Correct answer: B. a=b
Antisymmetry of a partial order implies a=b.
Question 153. For f(x)=2x+1, what is f(3)?
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Correct answer: B. 7
Substitute x=3: 2(3)+1 = 7.
Question 154. Which map on the real numbers is one-to-one? (variant 1)
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Correct answer: A. f(x)=1x+1
A linear function with nonzero slope is injective on the real numbers.
Question 155. For f(x)=2x+2, what is f(4)?
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Correct answer: D. 10
Substitute x=4: 2(4)+2 = 10.
Question 156. Which map on the real numbers is one-to-one? (variant 2)
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Correct answer: C. f(x)=2x+1
A linear function with nonzero slope is injective on the real numbers.
Question 157. For f(x)=2x+3, what is f(5)?
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Correct answer: B. 13
Substitute x=5: 2(5)+3 = 13.
Question 158. Which map on the real numbers is one-to-one? (variant 3)
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Correct answer: A. f(x)=3x+1
A linear function with nonzero slope is injective on the real numbers.
Question 159. For f(x)=2x+4, what is f(6)?
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Correct answer: D. 16
Substitute x=6: 2(6)+4 = 16.
Question 160. Which map on the real numbers is one-to-one? (variant 4)
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Correct answer: C. f(x)=4x+1
A linear function with nonzero slope is injective on the real numbers.
Question 161. For f(x)=2x+5, what is f(7)?
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Correct answer: B. 19
Substitute x=7: 2(7)+5 = 19.
Question 162. Which map on the real numbers is one-to-one? (variant 5)
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Correct answer: A. f(x)=5x+1
A linear function with nonzero slope is injective on the real numbers.
Question 163. For f(x)=2x+6, what is f(8)?
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Correct answer: D. 22
Substitute x=8: 2(8)+6 = 22.
Question 164. Which map on the real numbers is one-to-one? (variant 6)
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Correct answer: C. f(x)=6x+1
A linear function with nonzero slope is injective on the real numbers.
Question 165. For f(x)=2x+7, what is f(9)?
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Correct answer: B. 25
Substitute x=9: 2(9)+7 = 25.
Question 166. Which map on the real numbers is one-to-one? (variant 7)
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Correct answer: A. f(x)=7x+1
A linear function with nonzero slope is injective on the real numbers.
Question 167. For f(x)=2x+8, what is f(10)?
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Correct answer: D. 28
Substitute x=10: 2(10)+8 = 28.
Question 168. Which map on the real numbers is one-to-one? (variant 8)
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Correct answer: C. f(x)=8x+1
A linear function with nonzero slope is injective on the real numbers.
Question 169. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a3.
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Correct answer: D. 6
The recurrence sums 1+2+…+3 = 3(3+1)/2 = 6.
Question 170. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a4.
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Correct answer: B. 10
The recurrence sums 1+2+…+4 = 4(4+1)/2 = 10.
Question 171. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a5.
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Correct answer: D. 15
The recurrence sums 1+2+…+5 = 5(5+1)/2 = 15.
Question 172. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a6.
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Correct answer: B. 21
The recurrence sums 1+2+…+6 = 6(6+1)/2 = 21.
Question 173. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a7.
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Correct answer: D. 28
The recurrence sums 1+2+…+7 = 7(7+1)/2 = 28.
Question 174. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a8.
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Correct answer: B. 36
The recurrence sums 1+2+…+8 = 8(8+1)/2 = 36.
Question 175. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a9.
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Correct answer: D. 45
The recurrence sums 1+2+…+9 = 9(9+1)/2 = 45.
Question 176. A sequence is defined by a₁=1 and aₙ=aₙ₋₁+n for n≥2. Find a10.
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Correct answer: B. 55
The recurrence sums 1+2+…+10 = 10(10+1)/2 = 55.
