Discrete Mathematics - End Semester Examination - 2023

2023Semester 2Civil-CAEnd Semester
Bihar Engineering University, Patna
End Semester Examination - 2023

Discrete Mathematics

Time: 03 HoursCode: 100404Full Marks: 70

Instructions:

  1. The marks are indicated in the right-hand margin.
  2. There are NINE questions in this paper.
  3. Attempt FIVE questions in all.
  4. Question No. 1 is compulsory.
Q.1 Write the answer of the following (Any seven question only):[14]
  1. Let A be the set odd positive integers less than 10. Then cardinality of A, |A| is

    1. 5
    2. 9
    3. 6
    4. 4
  2. If m is the number of objects (pigeons) and n is the number of boxes (pigeonholes), then the function is both one-to-one and onto if

    1. \( m < n \)
    2. \( m = n \)
    3. \( m > n \)
    4. none of these
  3. If \( A \times B = B \times A \), (Where A and B are general matrices) then

    1. \( A = \phi \)
    2. \( A = B' \)
    3. \( B = A \)
    4. \( A' = B \)
  4. A partial ordered relation is transitive, reflexive and

    1. Anti symmetric
    2. bi symmetric
    3. anti reflexive
    4. asymmetric
  5. If B is a Boolean Algebra, then which of the following is true

    1. B is a finite but complemented lattice
    2. B is a finite, complemented and distributive lattice
    3. B is a finite, Distributive but not complemented lattice
    4. B is not distributive lattice
  6. \( P \rightarrow q \) is logically equivalent to

    1. \( -q \rightarrow p \)
    2. \( -P \rightarrow q \)
    3. \( -P \wedge q \)
    4. \( -p \vee q \)
  7. If \( f(x) = \cos x \) and \( g(x) = x^3 \) then \( (f \circ g)(x) \) is

    1. \( (\cos x)^3 \)
    2. \( \cos 3x \)
    3. \( x^{(\cos x)^3} \)
    4. \( \cos(x^3) \)
  8. The number of distinguishable permutations of the letters in the word BANANA are

    1. 60
    2. 36
    3. 20
    4. 10
  9. Which of the following pair is not congruent modulo 7?

    1. 10, 24
    2. 25, 56
    3. -31, -15
    4. -64, -15
  10. Let \( N=\{1,2,3,........\} \) be ordered by divisibility, which of the following subset is totally ordered

    1. (2, 6, 24)
    2. (3, 5, 15)
    3. (2, 9, 16)
    4. (4, 15, 30)
Q.2 Solve both questions :[7+7=14]
  1. Let \( A = B = \{x | -1 \le x \le 1\} \) for each of the following functions state where it is injective, surjective or bijective: i) \( g(x) = \sin \pi x \) ii) \( b(x) = \frac{2x}{3} \)

  2. Let \( f(x) = x+2 \), \( g(x) = x-2 \), \( h(x) = 3x \) find (i) \( f \circ g \) (ii) \( f \circ g \circ h \)

Q.3 Solve both questions :[7+7=14]
  1. Find the power set of each of these sets: i) \( \{a,b\} \) ii) \( \{\phi, \{\phi\}\} \)

  2. Use Cantor's diagonal argument to prove that set F of all functions \( f: (0,1) \rightarrow R \) has larger Cardinality than |R|.

Q.4 Solve this question :[14]
  1. Determine if the sets are countable or uncountable: a.) the set A of all function \( g: Z_{+} \rightarrow Z_{+} \) b.) The set B of all functions \( f: Z_{+} \rightarrow \{0,1\} \)

Q.5 Solve this question :[14]
  1. Prove the following by using the principle of mathematical induction for all \( n \in N \): \( 1^3 + 2^3 + 3^3 + \dots + n^3 = \left(\frac{n(n+1)}{2}\right)^2 \)

Q.6 Solve this question :[14]
  1. State and prove Division algorithm theorem well-ordering principle.

Q.7 Solve both questions :[7+7=14]
  1. Check the validity of the following argument all integers are rational numbers. Some integers are powers of 5. Therefore, some rational numbers are powers of 5.

  2. A grocery store employee is stocking apples. Each apple is a different color. There are 10 apples left in the box and the employee pulls out 2 of them at random. What is the probability that the employee pulls out one pink apple and yellow apple?

Q.8 Solve this question :[14]
  1. Let \( \Psi: G \rightarrow H \) be a homomorphism of groups. Show that if \( a \in G \) has order n, then \( \Psi(a) \in H \) has order dividing n.

Q.9 Solve both questions :[7+7=14]
  1. Consider the given graph. (a) Does a Hamiltonian path exist? If so describe it. If not say why not.

    (b) Does an Eulerian path exist? If so describe it. If not say why not.

    Question Diagram