Available Questions 152 found Page 8 of 8
Standalone Questions
#1004
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
MEDIUM
2025
JEE Main 2025 (Online) 2nd April Evening Shift
Competency
4 Marks
Let $A = {1, 2, 3, ..., 100}$ and $R$ be a relation on $A$ such that $R = {(a, b) : a = 2b + 1}$. Let $(a_1, a_2), (a_2, a_3), (a_3, a_4), ..., (a_k, a_{k+1})$ be a sequence of $k$ elements of $R$ such that the second entry of an ordered pair is equal to the first entry of the next ordered pair. Then the largest integer k , for which such a sequence exists, is equal to :
(A) 6
(B) 8
(C) 7
(D) 5
Key: A
Sol:
Sol:
The relation $R$ is defined on the set $A = {1, 2, 3, ..., 100}$ such that $R = {(a, b) : a = 2b + 1}$. We need to find the largest integer $k$ for which there exists a sequence of $k$ ordered pairs from $R$ where the second element of each pair is the first element of the next pair.
The sequence in terms of $k$ is: $(a_1, a_2), (a_2, a_3), ..., (a_k, a_{k+1})$. Here, each $a_i$ satisfies the equation $a_i = 2a_{i+1} + 1$. Consequently, $a_1 = 2a_2 + 1$, making $a_1$ an odd number.
Let's examine the pattern:
$a_2 = 2a_3 + 1$, implying $a_1 = 2(2a_3 + 1) + 1 = 4a_3 + 3$.
$a_3 = 2a_4 + 1$, leading to $a_1 = 4(2a_4 + 1) + 3 = 8a_4 + 7$.
Continuing this pattern, we find:
$a_k = 2a_{k+1} + 1 \implies a_1 = 2^k \cdot a_{k+1} + (2^k - 1)$ where $a_{k+1}$ needs to be in set $A$. This implies:
$a_{k+1} = \frac{a_1 + 1 - 2^k}{2^k}$
Thus, $2^k \mid (a_1 + 1)$. The task is to find the highest $k$ where $2^k$ divides any $e_i$ in ${2, ..., 101}$.
The largest power of 2 that divides an element within this range determines $k$.
After computation, we find that $k$ can be a maximum of 6 because $2^6 = 64$ divides $95+1 = 96$, but $2^7 = 128$ does not divide any $e_i$ for $e_i \in A$. Therefore, the maximum $k$ is 6.
The sequence corresponding to this maximum $k$ is: $(95, 47), (47, 23), (23, 11), (11, 5), (5, 2)$
#1002
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
HARD
2025
JEE Main 2025 (Online) 3rd April Evening Shift
Competency
4 Marks
Let $A = \{-2, -1, 0, 1, 2, 3\}$. Let R be a relation on $A$ defined by $xRy$ if and only if $y = \max\{x, 1\}$. Let $l$ be the number of elements in R. Let $m$ and $n$ be the minimum number of elements required to be added in R to make it reflexive and symmetric relations, respectively. Then $l + m + n$ is equal to
(A) 11
(B) 12
(C) 14
(D) 13
Key: B
Sol:
Sol:
The relation $R$ is defined such that $y = \max(x, 1)$. Therefore, we find the following pairs:
$x = -2 \implies y = \max(-2, 1) = 1$, so $(-2, 1) \in R$.
$x = -1 \implies y = \max(-1, 1) = 1$, so $(-1, 1) \in R$.
$x = 0 \implies y = \max(0, 1) = 1$, so $(0, 1) \in R$.
$x = 1 \implies y = \max(1, 1) = 1$, so $(1, 1) \in R$.
$x = 2 \implies y = \max(2, 1) = 2$, so $(2, 2) \in R$.
$x = 3 \implies y = \max(3, 1) = 3$, so $(3, 3) \in R$.
Thus, $R = \{(-2, 1), (-1, 1), (0, 1), (1, 1), (2, 2), (3, 3)\}$, and $l = 6$.
To make $R$ reflexive, we need to add $(-2, -2), (-1, -1), (0, 0)$. Thus, $m = 3$.
To make $R$ symmetric, we need to add $(1, -2), (1, -1), (1, 0)$. Thus, $n = 3$.
Therefore, $l + m + n = 6 + 3 + 3 = 12$.
#997
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
UNDERSTAND
HARD
2025
JEE Main 2025 (Online) 4th April Morning Shift
Competency
4 Marks
Consider the sets $A = \{(x, y) \in R \times R : x^2 + y^2 = 25\}$, $B = \{(x, y) \in R \times R: x^2 + 9y^2 = 144\}$, $C = \{(x, y) \in Z \times Z: x^2 + y^2 \leq 4\}$ and $D = A \cap B$. The total number of one-one functions from the set $D$ to the set $C$ is:
(A) 15120
(B) 18290
(C) 17160
(D) 19320
Key: C
Sol:
Sol:
$A = \{(x, y) \in R \times R : x^2 + y^2 = 25\}$, $B = \{(x, y) \in R \times R: x^2 + 9y^2 = 144\}$
$x^2 + 9y^2 - (x^2 + y^2) = 144 - 25$
Plug in $y^2 = \frac{119}{8}$ into either equation to find $x$.
$x^2 = 25 - \frac{119}{8}$
$x^2 = \frac{200 - 119}{8}$
$x^2 = \frac{81}{8}$
$x = \pm \sqrt{\frac{81}{8}}$, $y = \pm \sqrt{\frac{119}{8}}$
Now, $C = \{(x, y) \in Z \times Z: x^2 + y^2 \leq 4\}$
Valid points are $(-2, 0), (-1, -1), (-1, 0), (-1, 1), (0, -2), (0, -1), (0, 0), (0, 1), (0, 2), (1, -1), (1, 0), (1, 1)$
$\therefore$ Total valid points in $C = 13$
$\Rightarrow$ There are 4 distinct real points in set $D$
$\therefore$ The number of one-one functions from $D$ to $C$
$\Rightarrow {}^{13}P_4 \Rightarrow \frac{13!}{(13-4)!} = \frac{13!}{9!} = 17160$
#994
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
HARD
2025
JEE Main 2025 (Online) 8th April Evening Shift
Competency
4 Marks
Let A = {0, 1, 2, 3, 4, 5}. Let R be a relation on A defined by (x, y) ā R if and only if max{x, y} ā {3, 4}. Then among the statements
(S1): The number of elements in R is 18, and
(S2): The relation R is symmetric but neither reflexive nor transitive
(S1): The number of elements in R is 18, and
(S2): The relation R is symmetric but neither reflexive nor transitive
(A) both are false
(B) only (S1) is true
(C) only (S2) is true
(D) both are true
Key: C
Sol:
Sol:
To evaluate the relation $R$ on the set $A = {0, 1, 2, 3, 4, 5}$, we first need to understand the conditions for an element $(x, y)$ to be in $R$. Specifically, $(x, y) ā R$ if and only if $max{x,y} ā {3,4}$.
Considering this, let's list the pairs:
For $max{x, y} = 3$, the possible pairs are:
$(0, 3), (3, 0), (1, 3), (3, 1), (2, 3), (3, 2), (3, 3)$
For $max{x, y} = 4$, the possible pairs are:
$(0, 4), (4, 0), (1, 4), (4, 1), (2, 4), (4, 2), (3, 4), (4, 3), (4, 4)$
Combining these, the set $R$ consists of the following elements:
$R = {(0, 3), (3, 0), (1, 3), (3, 1), (2, 3), (3, 2), (3, 3), (0, 4), (4, 0), (1, 4), (4, 1), (2, 4), (4, 2), (3, 4), (4, 3), (4, 4)}$
This gives us a total of 16 elements in $R$, not 18 as initially claimed in statement $S1$.
Next, we analyze the properties of the relation $R$:
Reflexivity: A relation is reflexive if $(x, x) ā R$ for all $x ā A$. For example, $(0, 0), (1, 1), (2, 2)$ are not in $R$, so $R$ is not reflexive.
Symmetry: A relation is symmetric if whenever $(a, b) ā R$, then $(b, a) ā R$ as well. For all pairs $(x, y)$ listed, both $(x, y)$ and $(y, x)$ are present. Thus, $R$ is symmetric.
Transitivity: A relation is transitive if whenever $(a, b) ā R$ and $(b, c) ā R$, then $(a, c) ā R$. An example where transitivity fails is $(0, 3)$ and $(3, 1)$ are in $R$ but $(0, 1)$ is not in $R$. Therefore, $R$ is not transitive.
In conclusion, statement $S2$ is correct as $R$ is symmetric but neither reflexive nor transitive.
#987
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
HARD
2025
JEE Main 2025 (Online) 3rd April Evening Shift
Competency
4 Marks
If the probability that the random variable $X$ takes the value $x$ is given by
$P(X=x) = k(x+1)3^{-x}, x = 0, 1, 2, 3 \dots$, where $k$ is a constant, then $P(X \geq 3)$ is equal to
$P(X=x) = k(x+1)3^{-x}, x = 0, 1, 2, 3 \dots$, where $k$ is a constant, then $P(X \geq 3)$ is equal to
(A) $\frac{1}{9}$
(B) $\frac{8}{27}$
(C) $\frac{7}{27}$
(D) $\frac{4}{9}$
Key: A
Sol:
Sol:
To find $P(X \geq 3)$, we first determine the constant $k$ using the total probability for $X$.
The probability $P(X = x)$ is given by:
$P(X= x) = k(x+1) \cdot 3^{-x}, x= 0,1,2,3,\dots$
The total probability must equal 1:
$s = \sum_{x=0}^{\infty} k(x+1) \cdot 3^{-x}$
Calculating that series:
$s = k3^0 + 2\frac{k}{3} + 3\frac{k}{3^2} + \dots$
Therefore, dividing the series by 3:
$\frac{s}{3} = \frac{k}{3} + 2\frac{k}{3^2} + \dots$
Subtracting these:
$s - \frac{s}{3} = k + \frac{k}{3} + \frac{k}{3^2} + \dots$
The resulting series is a geometric series:
$2\frac{s}{3} = k(1 + \frac{1}{3} + \frac{1}{3^2} + \dots )$
The sum of the infinite geometric series is:
$2\frac{s}{3} = k \cdot \frac{1}{1 - \frac{1}{3}} = \frac{3k}{2}$
Equating:
$s = \frac{9k}{4} = 1$
Thus, solving for $k$:
$k = \frac{4}{9}$
Next, compute $P(X \geq 3)$:
$P(X \geq 3) = 1 - (P(X=0) + P(X=1) + P(X=2))$
Calculating these:
$P(X=0) = k = \frac{4}{9}$
$P(X=1) = 2\frac{k}{3} = \frac{8}{27}$
$P(X=2) = 3\frac{k}{9} = \frac{4}{27}$
Adding these probabilities:
$P(X=0) + P(X=1) + P(X=2) = \frac{4}{9} + \frac{8}{27} + \frac{4}{27} = \frac{8}{9}$
Finally, calculate $P(X \geq 3)$:
$P(X \geq 3) = 1 - \frac{8}{9} = \frac{1}{9}$
#986
Mathematics
Statistics and Probability
MCQ_SINGLE
APPLY
HARD
2025
JEE Main 2025 (Online) 4th April Morning Shift
Competency
4 Marks
A box contains 10 pens of which 3 are defective. A sample of 2 pens is drawn at random and let $X$ denote the number of defective pens. Then the variance of $X$ is
(A) $\frac{11}{15}$
(B) $\frac{2}{15}$
(C) $\frac{3}{5}$
(D) $\frac{28}{75}$
Key: D
Sol:
Sol:
$X$\n$P(X)S$\n$XP(X)$\n$\left(X_i-\mu\right)^2$ SP_i X\left(X_i-\mu\right)^2$\n$X=0$\n$\frac{{}^7 C_2}{{}^{10} C_2}$\n0\nS\left(0-\frac{3}{5}\right)^2$\n$\frac{7}{15}\left(\frac{9}
#964
Mathematics
Practice
MCQ_SINGLE
APPLY
HARD
AI Import
Competency
1 Marks
Let A be the set of all functions $f: \mathbb{Z} \rightarrow \mathbb{Z}$ and R be a relation on A such that $R = \{(f, g): f(0) = g(1)$ and $f(1) = g(0)\}$. Then R is :
(A) Symmetric and transitive but not reflective
(B) Symmetric but neither reflective nor transitive
(C) Transitive but neither reflexive nor symmetric
(D) Reflexive but neither symmetric nor transitive
Key: B
Sol:
Sol:
Symmetric but neither reflective nor transitive
#963
Mathematics
Practice
MCQ_SINGLE
APPLY
HARD
AI Import
Competency
1 Marks
Let A = {1, 2, 3, ...., 100} and R be a relation on A such that R = {(a, b): a = 2b+1}. Let (a1, аг), (аг, аз), (аз, а4),...., (ak, ak+1) be a sequence of k elements of R such that the second entry of an ordered pair is equal to the first entry of the next ordered pair. Then the largest integer k, for which such a sequence exists, is
equal to :
equal to :
(A) 6
(B) 8
(C) 7
(D) 5
Key: D
Sol:
Sol:
The relation R is defined on the set A = {1, 2, 3, ..., 100} such that R = {(a, b): a = 2b + 1}. We need to find
the largest integer k for which there exists a sequence of k ordered pairs from R where the second element of each
pair is the first element of the next pair.
#962
Mathematics
Practice
MCQ_SINGLE
APPLY
HARD
Smart Import
Competency
1 Marks
Let A = {-3, -2, -1, 0, 1, 2, 3}. Let R be a relation on A defined by xRy if and only if 0 < x² + 2y < 4. Let l be
the number of elements in R and m be the minimum number of elements required to be added in R to make it a
reflexive relation. Then l + m is equal to
the number of elements in R and m be the minimum number of elements required to be added in R to make it a
reflexive relation. Then l + m is equal to
(A) 18
(B) 20
(C) 17
(D) 19
Key: A
Sol:
Sol:
18
#961
Mathematics
Practice
MCQ_SINGLE
APPLY
MEDIUM
Competency
Marks
Let A = {-2, -1, 0, 1, 2, 3}. Let R be a relation on A defined by Ry if and only if y = max{x, 1}. Let I be the
number of elements in R. Let m and n be the minimum number of elements required to be added in R to make it
reflexive and symmetric relations, respectively. Then l + m + n is equal to
number of elements in R. Let m and n be the minimum number of elements required to be added in R to make it
reflexive and symmetric relations, respectively. Then l + m + n is equal to
(A) 11
(B) 12
(C) 14
(D) 13
Key: B
Sol:
Sol:
#960
Mathematics
Practice
MCQ_SINGLE
APPLY
HARD
2025
JEE Main 2025
Competency
0 Marks
Let A = {0, 1, 2, 3, 4, 5}. Let R be a relation on A defined by (x, y) ā R if and only if max{x,y} ā {3, 4}. Then among the statements
(Sā): The number of elements in R is 18, and
(S2): The relation R is symmetric but neither reflexive nor transitive
(Sā): The number of elements in R is 18, and
(S2): The relation R is symmetric but neither reflexive nor transitive
(A) both are false
(B) only (Sā) is true
(C) only (S2) is true
(D) both are true
Key: C
Sol:
Sol:
ok
#715
Mathematics
Practice
ASSERTION_REASON
APPLY
MEDIUM
2020
Competency
4 Marks
Assertion: The boiling point of water is higher at lower elevations. Reason: Atmospheric pressure increases as elevation decreases.
Key: Both true and R explains A
Sol:
Sol:
Boiling occurs when vapor pressure equals atmospheric pressure. Higher pressure requires higher temperature.