Tag: set concepts

Questions Related to set concepts

Let $G = {x | x$ is boy of your class$}$ and $H = {y | y$ is a girl of your class$}$. What type of sets G and H are?

  1. Finite sets

  2. Infinite sets

  3. Cannot be determined

  4. None of these


Correct Option: A
Explanation:

Since the number of boys and girls in a class are always finite.
Therefore, set G and H are finite sets.

Classify $C = {..., -3, -2, -1, 0}$as 'finite' or 'infinite'. 

  1. Infinite

  2. Finite

  3. Data insufficient

  4. None of these


Correct Option: A
Explanation:

C is an infinite set as there are many numbers less than $ - 3 $

The set of all animals on the earth is a 

  1. Finite set

  2. Singleton set

  3. Null set

  4. Infinite set


Correct Option: A
Explanation:

Since the numbers of animals on the earth are countable(limited).
Therefore, set of all the animals on the earth is "finite" set.
Option A is correct.

Which of the following sets is non - empty ?

  1. Set of odd natural numbers divisible by 2

  2. ${x: x+4=0, x\in N}$

  3. Set of even prime numbers

  4. ${x:2< x< 3,x\in N}$


Correct Option: C
Explanation:

A non empty set has atleast one element.

From the given options we see that the SET C has one element which is $ 2 $

Which one of the following sets is infinite?

  1. Set of all integers greater than $5$

  2. Set ofall integers between $-10^{10}$ and $+10^{10}$

  3. Set of all prime numbers between $0$ and $10^{100}$

  4. Set of all even prime numbers


Correct Option: A
Explanation:

(2), (3), and (4) are finite sets.

The set of positive integers is ..................

  1. Infinite

  2. Finite

  3. Subset

  4. Empty


Correct Option: A
Explanation:

The set of positive integers is never ending. There is no such defined largest integer. Hence the set is infinite

For any three sets A, B and C, $A \cap (B \cup C)$ is

  1. $(A\cup B)\cup (B\cap C)$

  2. $(A\cap B)\cup (A\cap C)$

  3. $A\cup (B\cap C)$

  4. $(A\cup B)\cap (B\cup C)$


Correct Option: B
Explanation:

In the problem statement we are taking union of $B$ and $C$ and then taking its intersection with $A$.

This means $A\cap (B\cup C)$will contain elements that are in $A$ and are in either $B$ or $C$.
$\therefore A\cap (B\cup C) $ is equivalent to taking intersection of $A,B$ and $A,C$ and then taking there union i.e. $(A\cap B)\cup(A\cap C)$
Hence, option B is correct.

Define finite set.
Is $A=$set of animals on the earth a finite set.

  1. True

  2. False


Correct Option: A
Explanation:

Definition: A finite set is a set which has fixed or finite number of elements.
$A=$ Set of animals on the earth is a finite set because number of animals on the earth is large in number, but it is finite/fixed.

State which of the following are finite sets.
$(i){x:x\in N }$ and $(x-1)(x-2)=0.$
$(ii){x:x\in N }$ and $x$ is prime.
$(ii){x:x\in N }$ and $x$ is odd.

  1. $(i)$ only

  2. $(i),(ii)$ and $(iii)$

  3. $(i)$ and $(ii)$

  4. $(ii)$ and $(iii)$


Correct Option: A
Explanation:

$(i)(x-1)(x-2)=0$

$\Rightarrow x-1=0$ or $x-2=0$
$\Rightarrow x=1$ or $x=2$, Number of solutions of equation are finite.
$(ii){2,3,5,7,11,...}$, This set contains infinte number of elements.
$(iii){..,1,3,5,7,...}$, This set contains infinite number of elements. 

Which of the following sets is not a finite set ?

  1. ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }\le 1\le x+y,\ \ x,y\in R} $

  2. ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }\le 1\le x+y,\ \ x,y\in Z} $

  3. ${ (x,y):{ x }^{ 2 }\le y\le |x|,\ \ x,y\in Z} $

  4. ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }=1,\ \ x,y\in Z} $


Correct Option: A
Explanation:

The set ${ (x,y):{ x }^{ 2 }+{ y }^{ 2 }\le 1\le x+y,\ \ x,y\in R} $ consists of all the points in the first quadrant which lie inside the circle ${ x }^{ 2 }+{ y }^{ 2 }=1$ and above the line $x+y=1$ .So, it is not a finite set.
Option $A$ is correct.