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Jamb Mathematics - Lesson Notes on Sets for UTME Candidate

Feb 5 2025 04:43 PM

Osason

Jamb Updates

SETS | Jamb Mathematics

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"Get ready to explore the concept of 'Set' and discover how it applies to everyday life! Understanding sets helps us organize, categorize, and make sense of the world around us, from grouping objects to making informed decisions. As we dive into this topic, think about how sets shape the way we interact with people, ideas, and experiences in daily life."
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Are you preparing for your JAMB Mathematics exam and feeling a bit uncertain about how to approach the topic of Sets? Don’t worry—you’re in the right place! This lesson is here to break it down in a simple, clear, and engaging way, helping you build the strong foundation you need to succeed. Whether you're struggling with complex questions or just seeking a quick refresher, this guide will boost your understanding and confidence. Let’s tackle Sets together and move one step closer to achieving your exam success! Blissful learning.
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calculation-based questions along with their answers covering different types of sets:

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1. Empty Set (Null Set)
Q1: If A={xZx2=1}A = \{ x \in \mathbb{Z} \mid x^2 = -1 \}, what is n(A)n(A), the number of elements in AA?
  • A: Since no integer satisfies x2=1x^2 = -1, AA is an empty set. Thus, n(A)=0n(A) = 0.
Q2: Let B={xxB = \{ x \mid x is a prime number less than 2 }. Determine B|B|.
  • A: The only prime number less than 2 is 1, which is not prime. So, BB is empty, and B=0|B| = 0.

2. Universal Set
Q3: If the universal set is U={1,2,3,4,5,6,7,8,9,10}U = \{1,2,3,4,5,6,7,8,9,10\}, and A={2,4,6,8}A = \{2,4,6,8\}, find UA|U - A|.
  • A: The complement of AA in UU is UA={1,3,5,7,9,10}U - A = \{1,3,5,7,9,10\}, so UA=6|U - A| = 6.
Q4: Given U={x1x20,xN}U = \{x \mid 1 \leq x \leq 20, x \in \mathbb{N} \} and A={xxA = \{ x \mid x is an even number in UU}, find Ac|A^c|.
  • A: The even numbers in UU are {2,4,6,8,10,12,14,16,18,20}\{2,4,6,8,10,12,14,16,18,20\}, so A=10|A| = 10. The complement AcA^c contains the odd numbers, also 10 in count. Thus, Ac=10|A^c| = 10.

3. Complement of a Set
Q5: If U={1,2,3,4,5,6,7,8,9,10}U = \{1,2,3,4,5,6,7,8,9,10\} and A={2,4,6,8,10}A = \{2,4,6,8,10\}, compute Ac|A^c|.
  • A: The complement Ac=UA={1,3,5,7,9}A^c = U - A = \{1,3,5,7,9\}, so Ac=5|A^c| = 5.
Q6: Given U={xZ5x5}U = \{ x \in \mathbb{Z} \mid -5 \leq x \leq 5 \} and A={xxA = \{ x \mid x is a non-negative integer}, find Ac|A^c|.
  • A: The non-negative integers are {0,1,2,3,4,5}\{0,1,2,3,4,5\}, so A=6|A| = 6. The complement Ac={5,4,3,2,1}A^c = \{-5,-4,-3,-2,-1\}, so Ac=5|A^c| = 5.

4. Subsets
Q7: How many subsets does the set A={1,2,3,4}A = \{1,2,3,4\} have?
  • A: The number of subsets is 2n=24=162^n = 2^4 = 16.
Q8: If B={a,b,c,d,e}B = \{a,b,c,d,e\}, find the number of proper subsets of BB.
  • A: The total subsets are 25=322^5 = 32, and the number of proper subsets is 321=3132 - 1 = 31.

5. Finite and Infinite Sets
Q9: If C={xxC = \{x \mid x is a multiple of 3 and x<30x < 30}, find C|C|.
  • A: The elements are {3,6,9,12,15,18,21,24,27}\{3,6,9,12,15,18,21,24,27\}, so C=9|C| = 9.
Q10: If D={xxD = \{ x \mid x is a perfect square and x100}x \leq 100 \}, find D|D|.
  • A: The perfect squares are {1,4,9,16,25,36,49,64,81,100}\{1,4,9,16,25,36,49,64,81,100\}, so D=10|D| = 10.

6. Infinite Set
Q11: Let E={xxE = \{ x \mid x is a prime number}. Is EE finite or infinite?
  • A: The set of prime numbers is infinite.
Q12: The set F={xxF = \{ x \mid x is a natural number greater than 0 }. Determine if FF is finite or infinite.
  • A: The set of natural numbers is infinite.

7. Disjoint Sets
Q13: If G={1,2,3,4,5}G = \{1,2,3,4,5\} and H={6,7,8,9,10}H = \{6,7,8,9,10\}, find GH|G \cap H|.
  • A: The sets have no common elements, so GH=0|G \cap H| = 0.
Q14: Given I={xxI = \{x \mid x is an even number} and J={xxJ = \{x \mid x is an odd number}, are II and JJ disjoint?
  • A: Yes, because no number can be both even and odd.

8. Union and Intersection of Sets
Q15: If K={1,3,5,7}K = \{1,3,5,7\} and L={2,4,6,8}L = \{2,4,6,8\}, find KL|K \cup L|.
  • A: KL=K+L=4+4=8|K \cup L| = |K| + |L| = 4 + 4 = 8.
Q16: Given M={a,b,c,d}M = \{a,b,c,d\} and N={b,c,e,f}N = \{b,c,e,f\}, find MN|M \cap N|.
  • A: The common elements are {b,c}\{b,c\}, so MN=2|M \cap N| = 2.

9. Cartesian Product
Q17: If A={1,2}A = \{1,2\} and B={x,y,z}B = \{x,y,z\}, find A×B|A \times B|.
  • A: The Cartesian product has A×B=2×3=6|A| \times |B| = 2 \times 3 = 6 elements.
Q18: If P={a,b,c}P = \{a,b,c\} and Q={1,2,3,4}Q = \{1,2,3,4\}, how many ordered pairs exist in P×QP \times Q?
  • A: P×Q=3×4=12|P \times Q| = 3 \times 4 = 12.

10. Power Set
Q19: If S={a,b}S = \{a,b\}, how many elements are in the power set P(S)P(S)?
  • A: The power set contains 22=42^2 = 4 elements: {,{a},{b},{a,b}}\{\emptyset, \{a\}, \{b\}, \{a,b\} \}.
Q20: If T={1,2,3,4,5}T = \{1,2,3,4,5\}, find P(T)|P(T)|.
  • A: The number of subsets is 25=322^5 = 32, so P(T)=32|P(T)| = 32.
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Calculation problems involving Cardinality of Sets

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1. Basic Cardinality
Q1: If A={1,2,3,4,5,6,7,8,9,10}A = \{1,2,3,4,5,6,7,8,9,10\}, find A|A|.
  • A: The set has 10 elements, so A=10|A| = 10.
Q2: Given B={a,b,c,d,e}B = \{a, b, c, d, e\}, determine B|B|.
  • A: BB contains 5 elements, so B=5|B| = 5.

2. Union of Two Sets
Q3: If A={1,2,3,4,5}A = \{1,2,3,4,5\} and B={4,5,6,7,8}B = \{4,5,6,7,8\}, find AB|A \cup B|.
  • A: AB={1,2,3,4,5,6,7,8}A \cup B = \{1,2,3,4,5,6,7,8\}, so AB=8|A \cup B| = 8.
Q4: If X={a,b,c}X = \{a, b, c\} and Y={b,c,d,e}Y = \{b, c, d, e\}, compute XY|X \cup Y|.
  • A: XY={a,b,c,d,e}X \cup Y = \{a, b, c, d, e\}, so XY=5|X \cup Y| = 5.

3. Intersection of Two Sets
Q5: If A={2,4,6,8,10}A = \{2,4,6,8,10\} and B={1,2,3,4,5,6}B = \{1,2,3,4,5,6\}, find AB|A \cap B|.
  • A: AB={2,4,6}A \cap B = \{2,4,6\}, so AB=3|A \cap B| = 3.
Q6: If M={x,y,z}M = \{x,y,z\} and N={w,x,y,z}N = \{w,x,y,z\}, compute MN|M \cap N|.
  • A: MN={x,y,z}M \cap N = \{x,y,z\}, so MN=3|M \cap N| = 3.

4. Cardinality Using the Inclusion-Exclusion Principle
Q7: Given P=12|P| = 12, Q=18|Q| = 18, and PQ=5|P \cap Q| = 5, find PQ|P \cup Q|.
  • A: Using PQ=P+QPQ|P \cup Q| = |P| + |Q| - |P \cap Q|, we get 12+185=2512 + 18 - 5 = 25.
Q8: If A=20|A| = 20, B=15|B| = 15, and AB=7|A \cap B| = 7, find AB|A \cup B|.
  • A: AB=20+157=28|A \cup B| = 20 + 15 - 7 = 28.

5. Complement of a Set
Q9: If the universal set UU has 50 elements and A=30|A| = 30, find Ac|A^c|.
  • A: Ac=UA=5030=20|A^c| = |U| - |A| = 50 - 30 = 20.
Q10: Given U={1,2,3,,100}U = \{1,2,3,\dots,100\} and B={xxB = \{ x \mid x is a multiple of 5 in UU}, find Bc|B^c|.
  • A: The multiples of 5 in UU are {5,10,15,,100}\{5,10,15,\dots,100\}, which is 20 elements. Bc=10020=80|B^c| = 100 - 20 = 80.

6. Disjoint Sets
Q11: If C={1,3,5,7}C = \{1,3,5,7\} and & D = {2,4,6,8} ,find, find |C \cap D| $.
  • A: CD=C \cap D = \emptyset, so CD=0|C \cap D| = 0.
Q12: Given X=40|X| = 40, Y=25|Y| = 25, and XY=0|X \cap Y| = 0, determine XY|X \cup Y|.
  • A: Since XX and YY are disjoint, XY=X+Y=40+25=65|X \cup Y| = |X| + |Y| = 40 + 25 = 65.

7. Subsets and Power Set
Q13: If E={a,b,c,d}E = \{a, b, c, d\}, find the number of subsets of EE.
  • A: The number of subsets is 2n=24=162^n = 2^4 = 16.
Q14: How many proper subsets does F={1,2,3,4,5,6}F = \{1,2,3,4,5,6\} have?
  • A: The total subsets are 26=642^6 = 64, and proper subsets are 641=6364 - 1 = 63.

8. Cartesian Product
Q15: If A={1,2,3}A = \{1,2,3\} and B={x,y}B = \{x,y\}, find A×B|A \times B|.
  • A: The number of ordered pairs is A×B=3×2=6|A| \times |B| = 3 \times 2 = 6.
Q16: If P={a,b,c,d}P = \{a,b,c,d\} and Q={1,2,3,4,5}Q = \{1,2,3,4,5\}, compute P×Q|P \times Q|.
  • A: P×Q=4×5=20|P \times Q| = 4 \times 5 = 20.

9. Difference of Sets
Q17: If G={1,2,3,4,5,6}G = \{1,2,3,4,5,6\} and H={2,4,6}H = \{2,4,6\}, compute GH|G - H|.
  • A: GH={1,3,5}G - H = \{1,3,5\}, so GH=3|G - H| = 3.
Q18: Given X={a,b,c,d,e}X = \{a,b,c,d,e\} and Y={b,d}Y = \{b,d\}, find XY|X - Y|.
  • A: XY={a,c,e}X - Y = \{a,c,e\}, so XY=3|X - Y| = 3.

10. Partition of a Set
Q19: A set SS is partitioned into three disjoint subsets A,B,CA, B, C with A=10|A| = 10, B=15|B| = 15, and C=25|C| = 25. Find S|S|.
  • A: S=A+B+C=10+15+25=50|S| = |A| + |B| + |C| = 10 + 15 + 25 = 50.
Q20: If a set TT is divided into four mutually exclusive subsets of sizes 8, 12, 20, and 30, find T|T|.
  • A: T=8+12+20+30=70|T| = 8 + 12 + 20 + 30 = 70.

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Calculation problems involving not more than three (3) Sets

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1. Basic Cardinality of Sets (Single Set)
Q1: If a universal set UU has 50 elements and a subset AA has 20 elements, how many elements are in AcA^c?
  • A: Ac=UA=5020=30|A^c| = |U| - |A| = 50 - 20 = 30.
Q2: Given A=15|A| = 15 and B=25|B| = 25, if AB=5|A \cap B| = 5, find AB|A \cup B|.
  • A: AB=A+BAB=15+255=35|A \cup B| = |A| + |B| - |A \cap B| = 15 + 25 - 5 = 35.

2. Two-Set Problems (Union and Intersection)
Q3: In a group of 40 students, 18 study Mathematics, 25 study Science, and 10 study both subjects. How many study at least one subject?
  • A: MS=M+SMS=18+2510=33|M \cup S| = |M| + |S| - |M \cap S| = 18 + 25 - 10 = 33.
Q4: If a survey shows 30 people like coffee, 20 like tea, and 10 like both, how many like either coffee or tea?
  • A: CT=C+TCT=30+2010=40|C \cup T| = |C| + |T| - |C \cap T| = 30 + 20 - 10 = 40.
Q5: If A=100|A| = 100, B=80|B| = 80, and AB=150|A \cup B| = 150, find AB|A \cap B|.
  • A: AB=A+BAB=100+80150=30|A \cap B| = |A| + |B| - |A \cup B| = 100 + 80 - 150 = 30.

3. Complement and Only-One Membership
Q6: In a group of 60 people, 35 own a car, 25 own a bike, and 15 own both. How many own only a car?
  • A: CB=CCB=3515=20|C - B| = |C| - |C \cap B| = 35 - 15 = 20.
Q7: If 50 students are surveyed and 30 like basketball, 20 like soccer, and 10 like both, how many like only one sport?
  • A: BS+SB=(3010)+(2010)=20+10=30|B - S| + |S - B| = (30 - 10) + (20 - 10) = 20 + 10 = 30.

4. Three-Set Problems (Union and Intersection)
Q8: If A=50|A| = 50, B=40|B| = 40, C=30|C| = 30, AB=20|A \cap B| = 20, BC=10|B \cap C| = 10, CA=15|C \cap A| = 15, and ABC=5|A \cap B \cap C| = 5, find ABC|A \cup B \cup C|.
  • A:
    ABC=A+B+CABBCCA+ABC|A \cup B \cup C| = |A| + |B| + |C| - |A \cap B| - |B \cap C| - |C \cap A| + |A \cap B \cap C| =50+40+30201015+5=80= 50 + 40 + 30 - 20 - 10 - 15 + 5 = 80
Q9: In a class of 80 students, 50 study Physics, 30 study Chemistry, and 40 study Biology. If 20 study both Physics and Chemistry, 15 study both Chemistry and Biology, 10 study both Physics and Biology, and 5 study all three, find how many study at least one subject.
  • A:
    PCB=P+C+BPCCBPB+PCB|P \cup C \cup B| = |P| + |C| + |B| - |P \cap C| - |C \cap B| - |P \cap B| + |P \cap C \cap B| =50+30+40201510+5=80= 50 + 30 + 40 - 20 - 15 - 10 + 5 = 80

5. Finding Exclusive Group Membership
Q10: A survey of 200 students shows that 90 own an iPhone, 70 own a Samsung, and 50 own a Google Pixel. If 30 own both an iPhone and Samsung, 20 own both a Samsung and a Pixel, 25 own both a Pixel and an iPhone, and 10 own all three, how many own only a Samsung?
  • A:
    S(IP)=SSISP+ISP|S - (I \cup P)| = |S| - |S \cap I| - |S \cap P| + |I \cap S \cap P| =703020+10=30= 70 - 30 - 20 + 10 = 30

6. Complement and Neither Category
Q11: If 150 people are surveyed, 90 watch Netflix, 80 watch Hulu, and 40 watch both, how many watch neither?
  • A:
    NcHc=UNH=150(90+8040)=150130=20|N^c \cap H^c| = |U| - |N \cup H| = 150 - (90 + 80 - 40) = 150 - 130 = 20
Q12: In a school of 300 students, 120 play football, 100 play basketball, and 80 play volleyball. If 40 play both football and basketball, 30 play both basketball and volleyball, 50 play both football and volleyball, and 20 play all three, how many play none?
  • A:
    U(FBV)=300(120+100+80403050+20)=300200=100|U - (F \cup B \cup V)| = 300 - (120 + 100 + 80 - 40 - 30 - 50 + 20) = 300 - 200 = 100

7. Miscellaneous Complex Problems
Q13: If A=60|A| = 60, B=70|B| = 70, C=80|C| = 80, AB=25|A \cap B| = 25, BC=35|B \cap C| = 35, CA=30|C \cap A| = 30, and ABC=15|A \cap B \cap C| = 15, find AcBcCc|A^c \cap B^c \cap C^c| in a universal set of 150.
  • A:
    AcBcCc=UABC|A^c \cap B^c \cap C^c| = |U| - |A \cup B \cup C| =150(60+70+80253530+15)=150135=15= 150 - (60 + 70 + 80 - 25 - 35 - 30 + 15) = 150 - 135 = 15
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Thank you for taking the time to read my blog post! Your interest and engagement mean so much to me, and I hope the content provided valuable insights and sparked your curiosity. Your journey as a student is inspiring, and it’s my goal to contribute to your growth and success.
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If you found the post helpful, feel free to share it with others who might benefit. I’d also love to hear your thoughts, feedback, or questions—your input makes this space even better. Keep striving, learning, and achieving! 😊📚✨
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