DISCRETE STRUCTURE MCQ SET 1


  1. Which of the following is tautology?

a.)x v y
b.)x v (~y)
c.)x v(~x)
d.)(x=<y)^(x<=y)
Ans.: c.)
Explanation: 

X   ~X   X V(~X)
T   F   T
F   T   T

Tip: ‘~’ denotes negation that is ‘1’ means ‘0’ and ‘0’ means ‘1’

‘V’ means ‘OR’ operator.

Side note: Tautolgy means all the results should be True(T) or 1

  1. Minimum number of individual shoes to be picked up from a dark room (containing 10 pair of shoes) if we have to get atleast one proper pair.

a.)3

b.)11

c.)10

d.)20

Ans.: b.)

Explanation of logic: There are 10 pair of shoes.

A single proper matching pair can be found out only when we pick the 11th shoe because till 10th shoe we cannot be very sure that we will get the right pair. But the 11th shoe that we take will definitely let us match the right pair surely. (LOGICAL REASONING QUESTION)

Note: May be asked in interviews too.

  1. Circle has how many vertices?

a.) No vetices

b.) 2 vertex

c.) 5 vertex

d.) Infinite vertices

 

Ans.: d.)

Note: A simple but logic question.

You can mark as much vertices as possible on a circle.

Example:

  1. The logic of pumping lemma is and example of

a.)Recursion

b.) Divide and conquer rule

c.) Pigeon hole principle

d.) Iteration

Ans.: c.)

  1. An undirected graph possesses an eulerian circuit only if it is connected and its vertices are

a.) All of even degree

b.) All of odd degree

c.) of any degree

d.) even in number

Ans.: a.)

  1. The number of edges in a complete graph with N vertices is equal to

a.) N(N-1)

b.) 2N-1

c.) N-1

d.) N(N-1)/2

Ans.: d.)

  1. The number of edges in a connected graph with ‘n’ vertices is

a.) n-1

b.) n(n-1)/2

c.) n^2

d.) 2n-1

Ans.: a.)

  1. A graph G           has

                     4,5

a.) 4 edges

b.) 5 edges

c.) 20 edges

d.) 15 edges

Ans.: c.)

Logic: Number of edges in Graph G(m,n)=m*n

  1. A self complemented,distributed lattice is

a.) Boolean algebra

b.) Modular lattice

c.) Complete lattice

d.) Self dual lattice.

Ans.: a.)

  1. A graph with all nodes of equal importance is called as

a.) Complete graph

b.) Regular graph

c.) Non regular graph

d.) Multigraph

Ans.: b.) 

  1. A partial ordered relation is transitive, reflexive and

a.) bisymmetric

b.) antisymmetric

c.) antireflexive

d.) asymmetric

Ans.: b.)

  1. If n is an integer, and n^2 is odd then ‘n’ is

a.) even

b.) odd

c.) even or odd

d.) prime

Ans.: b.)

Reason:

1.) Let n be 7 then,

n^2=49 

2.) Let n be 9 then,

n^2=81

In both cases, the result is an odd number 

Therefore, answer is odd.

 

1) A tour of G is a closed walk of graph G which includes every edge G at least once. A ….. tour of G is a tour which includes every edge of G exactly once ?

Hamiltonian

Planar

Isomorphic

Euler

 

Answer = D

Explanation: If some closed walk in a graph contains all the edges then the walk is called Euler.

2) Which of the following is not a type of graph ?

Euler

Hamiltonian

Tree

Path

 

Answer = D

Explanation:Path is a way from one node no another but not a graph.

3) Choose the most appropriate definition of plane graph ?

A graph drawn in a plane in such a way that any pair of edges meet only at their end vertices

A graph drawn in a plane in such a way that if the vertex set of graph can be partitioned into two non – empty disjoint subset X and Y in such a way that each edge of G has one end in X and one end in Y.

A simple graph which is Isomorphic to Hamiltonian graph

None of these

 

Answer = A

Explanation: No explanation for this question.

4) A continuous non – intersecting curve in the plane whose origin and terminus coincide ?

Planer

Jordan

Hamiltonian

All of these

 

Answer = B

Explanation: The jordan graph is the set of all vertices of minimum eccentricity that is the set of all vertices A where the greatest distance to other vertex B is minimal.

5) Polyhedral is…. ?

A simple connected graph

A plane graph

A graph in which the degree of every vertex and every face is atleast 3

All of above

 

Answer = D

Explanation: A polyhedral graph is the undirected graph formed from the vertices and edges of a convex polyhedron

 

6) A path in graph G, which contains every vertex of G once and only once ?

Eulartour

Hamiltonian Path

Eular trail

Hamiltonian tour

 

Answer = B

Explanation:A Hamiltonian circuit in a connected graph is defined as a closed walk that traverse every vertex of G exactly once except the starting vertex.

7) A minimal spanning tree of a graph G is…. ?

A spanning sub graph

A tree

Minimum weights

All of above

 

Answer = D

Explanation: A tree is said to be spanning tree of connected graph G if it is subgraph of G and contains all the vertices of G.

8) A tree having a main node, which has no predecessor is…. ?

Spanning tree

Rooted tree

Weighted tree

None of these

 

Answer = B

Explanation:A tree in which one vertex distinguish from all other is called rooted tree.

9) Diameter of a graph is denoted by diam(G) is defined by…. ?

max (e(v) : v belongs to V)

max( d(u,v) )

Both A and B

None of these

 

Answer = C

Explanation: The diameter of a graph G is largest distance between two vertices in a graph G.

 

10) A vertex of a graph is called even or odd depending upon ?

Total number of edges in a graph is even or odd

Total number of vertices in a graph is even or odd

Its degree is even or odd

None of these

 

Answer = C

Explanation: The vertex of a graph is called even or odd based on its degree.

 

 

 SET-4

 

 

1) Let A and B be any two arbitrary events then which one of the following is true ?

P( A intersection B) = P(A). P(B)

P(A union B) = P(A) + P(B)

P(AB) = P(A intersection B). P(B)

P(A union B) >= P(A) + P(B)

 

Answer = D

2) If X and Y be the sets. Then the set ( X – Y) union (Y- X) union (X intersection Y ) is equal to?

X union Y

Xc union Yc

X intersection Y

Xc intersection Yc

 

Answer = A

3) If G is an undirected planer graph on n vertices with e edges then ?

e<=n

e<=2n

e<=3n

None of these

 

Answer = B

4) Which of the following statement is false ?

G is connected and is circuitless

G is connected and has n edges

G is minimally connected graph

G is circuitless and has n-1 edges

 

Answer = B

5) Probability that two randomly selected cards from a set of two red and two black cards are of same color is ?

1 / 2

1 / 3

2 / 3

None of these

 

Answer = B

6) The number of circuits that can be created by adding an edge between any two vertices in a tree is ?

Two

Exactly one

At least two

None

 

Answer = B

7) In a tree between every pair of vertices there is ?

Exactly one path

A self loop

Two circuits

n number of paths

 

Answer = A

8) The minimum number of cards to be dealt from an arbitrarily shuffled deck of 52 cards to guarantee that three cards are from some same suit is ?

8

3

9

12

 

Answer = C

9) Context free languages are closed under ?

union, intersection

Intersection , complement

union , kleene star

Complement , kleene star

 

Answer = C

10) Let R be a symmetric and transitive relation on a set A. Then ?

R is reflexive and hence a partial order

R is reflexive and hence an equivalence relation

R is not reflexive and hence not an equivalence relation

None of above

 

Answer = D

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