Tag: maths

Questions Related to maths

If $A,B$ are two non-empty sets which of the following statement is false

  1. $A-B=A\cap \left( { B }^{ C } \right) $

  2. $A-B=A\cap \left( { A\cap B } \right) $

  3. $A-B=A-\left( { B }^{ C } \right) $

  4. $A-B=\left( { A\cup B } \right) -B$


Correct Option: C

If $A=\left{1, 2, 3\right}$, then the numbers of subsets of set $A$ containing element $3$, is 

  1. $24$

  2. $28$

  3. $8$

  4. $16$


Correct Option: C
Explanation:
The set $\left\{1, 2, 3\right\}$ has $8$ subsets. The first subset would be the null or empty subset, which contains none of the numbers: $\left\{\right\}$.
 The null set is a subset of every set. The other subsets would include some of the numbers in the set, but not all of them: $\left\{1\right\}$,$\left\{2\right\}$,$\left\{3\right\}$,$\left\{1,2\right\}$,$\left\{1,3\right\}$,$\left\{2,3\right\},\{1,2,3\}$

Let ${ a } _{ 1 },{ a } _{ 2 },{ a } _{ 3 },............{ a } _{ 10 }$ be in G.P. with ${ a } _{ i }>0$ for $i=1,2,....,10$ and $S$ be the set of pairs $(r,k),r\quad k\in N$ ( the set of natural numbers) for which
$\left| { log } _{ e }{ a } _{ 1 }^{ r }{ a } _{ 2 }^{ k }\quad { log } _{ e }{ a } _{ 2 }^{ r }{ a } _{ 3 }^{ k }\quad { log } _{ e }{ a } _{ 3 }^{ r }{ a } _{ 4 }^{ k }\ { log } _{ e }{ a } _{ 4 }^{ r }{ a } _{ 5 }^{ k }\quad { log } _{ e }{ a } _{ 5 }^{ r }{ a } _{ 6 }^{ k }\quad { log } _{ e }{ a } _{ 6 }^{ r }{ a } _{ 7 }^{ k }\ { log } _{ e }{ a } _{ 7 }^{ r }a _{ 8 }^{ k }\quad { log } _{ e }{ a } _{ 8 }^{ r }{ a } _{ 9 }^{ k }\quad { log } _{ e }{ a } _{ 9 }^{ r }{ a } _{ 10 }^{ k } \right| =0$
Then the number of elements in S, is :

  1. Infinitely many

  2. 4

  3. 10

  4. 2


Correct Option: A

Classify $A = {x | x$ is a multiple of $3}$ as 'finite' or 'infinite'.

  1. Finite

  2. Infinite

  3. Ambiguous

  4. Data insufficient


Correct Option: B
Explanation:

A will be an infinite set as we have many multiples of 3 such has 3, 6, 9, 12 and so on

Classify $D = {x | x = 2^n, n \in N}$ as 'finite' or 'infinite'.

  1. Infinite

  2. Finite

  3. Data insufficient

  4. None of these


Correct Option: A
Explanation:

Set D will be infinite as there will be infinite powers of 2 since n can be any natural number from 1 to infinity.

Classify $B = {y | y$ is a factor of $13}$ as 'finite' or 'infinite'.

  1. Infinite

  2. Finite

  3. Data insufficient

  4. None of these


Correct Option: B
Explanation:

B is a finite set as 13 has only two factors which are 1, and 13.

The set of fractions between the natural numbers 3 and 4 is a :

  1. Finite set

  2. Null set

  3. Infinite set

  4. Singleton set


Correct Option: C
Explanation:

We can have many fractions between the numbers 3 and 4.
Hence, this set is an infinite set

If $A$ is finite set. Let $n(A)$ denote the number of elements in $A$ and $B$ are finite sets, $A\neq B$ and $n(A) = n(B)$. Then $n(A\cap B)$ is

  1.  $ > n(A)$

  2.  $ < n(A)$

  3.  $ \neq n(A)$

  4.  $ \leq n(A)$


Correct Option: B

Identify the type of Set
$A= { x| x \epsilon N, 2 \leq x \leq 3}$

  1. Finite Set

  2. Infinite Set

  3. Null Set

  4. Singleton Set


Correct Option: A
Explanation:

We have to identify the type of set.

Given $A={x|x\in N, 2 \leq x \leq 3 }$

               $={2,3}$ which is a finite set.

Therefore $A$ is a finite set.

A finite set $S$ is given by $S={x:x\in N: x\le15}.$ Find the cardinality of its power set.

  1. 32952

  2. 16384

  3. 32768

  4. 16476


Correct Option: C
Explanation:

$S$ is given by $S={x:x\in N: x\le15}$
$S={1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}$
$\therefore n(S)=15$
The power set is set of all the possible subsets of $S.$
Number of elements in power set $=$ Total number of subsets
So, cardinality of power set $S=2^{15}=32768$