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Standalone Questions
#1003
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
2025
JEE Main 2025 (Online) 3rd April Morning Shift
KNOWLEDGE
4 Marks
Let $A = {-3, -2, -1, 0, 1, 2, 3}$. Let R be a relation on A defined by $xRy$ if and only if $0 \le x^2 + 2y \le 4$. 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
(A) 18
(B) 20
(C) 17
(D) 19
Key: A
Sol:
Sol:
First, we determine the pairs $(x, y)$ that satisfy the condition $0 \le x^2 + 2y \le 4$ for the given set $A = \{-3, -2, -1, 0, 1, 2, 3\}$.
For $y = -3$, $x^2 + 2(-3) \le 4 \implies x^2 \le 10$, so $x$ can be $-3$ or $3$.
For $y = -2$, $x^2 + 2(-2) \le 4 \implies x^2 \le 8$, so $x$ can be $-2$ or $2$.
For $y = -1$, $x^2 + 2(-1) \le 4 \implies x^2 \le 6$, so $x$ can be $-2$ or $2$.
For $y = 0$, $x^2 + 2(0) \le 4 \implies x^2 \le 4$, so $x$ can be $-2, -1, 0, 1, 2$.
For $y = 1$, $x^2 + 2(1) \le 4 \implies x^2 \le 2$, so $x$ can be $-1, 0, 1$.
For $y = 2$, $x^2 + 2(2) \le 4 \implies x^2 \le 0$, so $x$ can only be $0$.
Thus, the relation R consists of the following pairs:
$R = \{(3, -3), (-3, -3), (-2, -2), (2, -2), (-2, -1), (2, -1), (-2, 0), (-1, 0), (0, 0), (1, 0), (2, 0), (-1, 1), (0, 1), (1, 1), (0, 2)\}$.
The number of elements in R is $l = 15$.
To make R reflexive, it must include all pairs $(x, x)$ for every $x \in A$. The set A has 7 elements, so the reflexive relation must contain $(-3, -3), (-2, -2), (-1, -1), (0, 0), (1, 1), (2, 2), (3, 3)$. Currently, R has $(-3,-3), (-2, -2), (0,0), (1,1)$. So the missing pairs are $(-1, -1), (2, 2), (3, 3)$, meaning $m = 3$.
Therefore, $l + m = 15 + 3 = 18$.
#1001
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
2025
JEE Main 2025 (Online) 4th April Morning Shift
KNOWLEDGE
4 Marks
Consider the sets $A = \{(x, y) \in R \times R : x^2 + y^2 = 25\}$, $B = \{(x, y) \in R \times R : x^2 + 9y^2 = 144\}$, $C = \{(x, y) \in Z \times Z : x^2 + y^2 \le 4\}$ 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:
The given sets are $A = \{(x, y) \in R \times R : x^2 + y^2 = 25\}$ and $B = \{(x, y) \in R \times R : x^2 + 9y^2 = 144\}$. To find the intersection of A and B, we solve the system of equations. Subtracting the equation for A from the equation for B gives: $x^2 + 9y^2 - (x^2 + y^2) = 144 - 25$, which simplifies to $8y^2 = 119$, so $y^2 = \frac{119}{8}$. Substituting this into the equation for A, we get $x^2 = 25 - \frac{119}{8} = \frac{200 - 119}{8} = \frac{81}{8}$. Thus, $x = \pm \frac{9}{\sqrt{8}}$ and $y = \pm \frac{\sqrt{119}}{\sqrt{8}}$. Since $D = A \cap B$, the set D contains 4 points. Now, consider the set $C = \{(x, y) \in Z \times Z : x^2 + y^2 \le 4\}$. The integer pairs (x, y) that satisfy this condition are: $(\pm 2, 0)$, $(0, \pm 2)$, $(\pm 1, 0)$, $(0, \pm 1)$, $(\pm 1, \pm 1)$, and $(0, 0)$. Counting these points, we find that there are 13 such pairs. The number of one-to-one functions from D to C is the number of ways to choose 4 elements from C and arrange them, which is $P(13, 4) = \frac{13!}{(13-4)!} = \frac{13!}{9!} = 13 \times 12 \times 11 \times 10 = 17160$.
#999
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
2025
JEE Main 2025 (Online) 7th April Evening Shift
KNOWLEDGE
4 Marks
Let $A = \{ (\alpha, \beta) \in R \times R : |\alpha - 1| \leq 4 \text{ and } |\beta - 5| \leq 6 \}$ and $B = \{ (\alpha, \beta) \in R \times R : 16(\alpha - 2)^2 + 9(\beta - 6)^2 \leq 144 \}$. Then
(A) $A \subset B$
(B) $B \subset A$
(C) neither $A \subset B$ nor $B \subset A$
(D) $A \cup B = \{ (x, y) : -4 \leqslant x \leqslant 4, -1 \leqslant y \leqslant 11 \}$
Key: B
Sol:
Sol:
For set A, we have $|x - 1| \leq 4$ and $|y - 5| \leq 6$. This implies $-4 \leq x - 1 \leq 4$ and $-6 \leq y - 5 \leq 6$. Therefore, $-3 \leq x \leq 5$ and $-1 \leq y \leq 11$. For set B, we have $16(x - 2)^2 + 9(y - 6)^2 \leq 144$, which simplifies to $\frac{(x - 2)^2}{9} + \frac{(y - 6)^2}{16} \leq 1$. This represents an ellipse centered at $(2, 6)$ with semi-major axis 4 and semi-minor axis 3. From the diagram, it's clear that $B \subset A$.
#998
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
2025
JEE Main 2025 (Online) 8th April Evening Shift
KNOWLEDGE
4 Marks
Let $A = {0, 1, 2, 3, 4, 5}$. Let $R$ be a relation on $A$ defined by $(x, y) \in R$ if and only if $\max{x, y} \in {3, 4}$. 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 determine the elements in the relation $R$, we need to find all pairs $(x, y)$ such that $\max(x, y) \in {3, 4}$. The set $A = {0, 1, 2, 3, 4, 5}$.
If $\max(x, y) = 3$, the pairs are $(0, 3), (1, 3), (2, 3), (3, 3), (3, 0), (3, 1), (3, 2)$.
If $\max(x, y) = 4$, the pairs are $(0, 4), (1, 4), (2, 4), (3, 4), (4, 4), (4, 0), (4, 1), (4, 2), (4, 3)$.
Thus, the total number of elements in $R$ is $7 + 9 = 16$. Therefore, statement S1 is false.
For statement S2, we check the properties of $R$:
Reflexivity: $(0, 0)$ is not in $R$, so $R$ is not reflexive.
Symmetry: If $(x, y) \in R$, then $\max(x, y) \in {3, 4}$, which implies $\max(y, x) \in {3, 4}$, so $(y, x) \in R$. Thus, $R$ is symmetric.
Transitivity: $(0, 3) \in R$ and $(3, 1) \in R$, but $(0, 1)$ is not in $R$. Therefore, $R$ is not transitive.
Statement S2 is true since $R$ is symmetric but neither reflexive nor transitive.
#996
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
2025
JEE Main 2025 (Online) 4th April Evening Shift
KNOWLEDGE
4 Marks
Let $A = \{-3, -2, -1, 0, 1, 2, 3\}$ and R be a relation on A defined by $xRy$ if and only if $2x - y \in \{0, 1\}$. 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) 17
(B) 18
(C) 15
(D) 16
Key: A
Sol:
Sol:
$xRy \Leftrightarrow 2x - y \in \{0, 1\}$
$\Rightarrow y = 2x$ or $y = 2x - 1$
$A=\{-3,-2,-1, 0, 1, 2, 3\}$
$R = \{(-1,-2), (0,0), (1, 2), (-1, -3), (0, -1), (1, 1), (2,3)\}$
$\Rightarrow I=7$
For $R$ to be reflexive $(0,0), (1,1) \in R$
But other $(a, a)$ such that $2a - a \in \{0, 1\}$
$\Rightarrow a \in \{0, 1\}$
5 other pairs needs to be added
$\Rightarrow m=5$
$xRy \Rightarrow yRx$ to be symmetric
$(-1, -2) \Rightarrow (-2, -1)$
$(1, 2) \Rightarrow (2, 1)$
$(-1, -3) \Rightarrow (-3, -1)$
$(0, -1) \Rightarrow (-1, 0)$
$(2, 3) \Rightarrow (3, 2)$
$\Rightarrow 5$ needs to be added, $n=5$
$\Rightarrow l+m+n=17$
#995
Mathematics
Sets, Relations, and Functions
MCQ_SINGLE
APPLY
2025
JEE Main 2025 (Online) 7th April Evening Shift
KNOWLEDGE
4 Marks
Let $A = { (\alpha, \beta ) \in R \times R : |\alpha - 1| \leq 4$ and $|\beta - 5| \leq 6 }$
and $B = { (\alpha, \beta ) \in R \times R : 16(\alpha - 2)^{2}+ 9(\beta - 6)^{2} \leq 144 }$.
Then
and $B = { (\alpha, \beta ) \in R \times R : 16(\alpha - 2)^{2}+ 9(\beta - 6)^{2} \leq 144 }$.
Then
(A) A $A \subset B$
(B) B $B \subset A$
(C) C neither $A \subset B$ nor $B \subset A$
(D) D $A \cup B = { (x, y) : -4 \leqslant x \leqslant 4, -1 \leqslant y \leqslant 11 }$
Key: B
Sol:
Sol:
$A: |x-1| \leq 4$ and $|y-5| \leq 6$
$\Rightarrow -4 \leq x-1 \leq 4 \Rightarrow -6 \leq y-5 \leq 6$
$\Rightarrow -3 \leq x \leq 5 \Rightarrow -1 \leq y \leq 11$
$B : 16(x-2)^{2} + 9(y-6)^{2} \leq 144$
$B : \frac{(x-2)^{2}}{9} + \frac{(y-6)^{2}}{16} \leq 1$
From Diagram $B \subset A$
#993
Mathematics
Statistics and Probability
MCQ_SINGLE
APPLY
EASY
2025
JEE Main 2025 (Online) 28th January Morning Shift
KNOWLEDGE
4 Marks
Three defective oranges are accidently mixed with seven good ones and on looking at them, it is not possible to differentiate between them. Two oranges are drawn at random from the lot. If $x$ denote the number of defective oranges, then the variance of $x$ is
(A) 26/75
(B) 14/25
(C) 18/25
(D) 28/75
Key: D
Sol:
Sol:
Probability distribution
$x = 0$, $p = \frac{^7C_2}{^{10}C_2} = \frac{42}{90}$
$x = 1$, $p = \frac{^7C_1 \times ^3C_1}{^{10}C_2} = \frac{42}{90}$
$x = 2$, $p = \frac{^3C_2}{^{10}C_2} = \frac{6}{90}$
Now,
$\mu = \sum x_i p_i = \frac{42}{90} + \frac{12}{90} = \frac{54}{90}$
$\sigma^2 = \sum p_i x_i^2 - \mu^2 = \frac{42}{90} + \frac{24}{90} - (\frac{54}{90})^2$
$\Rightarrow \frac{66}{90} - (\frac{54}{90})^2$
$\sigma^2 \Rightarrow \frac{28}{75}$
#992
Mathematics
Statistics and Probability
MCQ_SINGLE
APPLY
EASY
2025
JEE Main 2025 (Online) 28th January Morning Shift
KNOWLEDGE
4 Marks
Two number $k_1$ and $k_2$ are randomly chosen from the set of natural numbers. Then, the probability that the value of $i^{k_1} + i^{k_2}$, ($i = \sqrt{-1}$) is non-zero, equals
(A) $\frac{3}{4}$
(B) $\frac{1}{2}$
(C) $\frac{1}{4}$
(D) $\frac{2}{3}$
Key: A
Sol:
Sol:
$i^{k_1} + i^{k_2} \ne 0 \Rightarrow i^{k_1} \rightarrow 4$ option for $i, -1, -i, 1$
Total cases $ \Rightarrow 4 \times 4 = 16$
Unfovourble cases $ \Rightarrow i^{k_1} + i^{k_2} = 0$
$ \{\begin{array}{c}1, -1 \\ -1, 1 \\ i, -i \\ -i, i\end{array}\}$
4 Cases $\Rightarrow$ Probability $ = \frac{16-4}{16} = \frac{3}{4}$
#991
Mathematics
Statistics and Probability
MCQ_SINGLE
APPLY
EASY
2025
JEE Main 2025 (Online) 28th January Evening Shift
KNOWLEDGE
4 Marks
Let S be the set of all the words that can be formed by arranging all the letters of the word GARDEN. From the set S, one word is selected at random. The probability that the selected word will NOT have vowels in alphabetical order is:
(A) $\frac{1}{4}$
(B) $\frac{1}{2}$
(C) $\frac{1}{3}$
(D) $\frac{2}{3}$
Key: B
Sol:
Sol:
A, E,G R D N
Probabllity $(P) = \frac{\text{favourable case}}{\text{Total case}}$
(when A & E are in order)
Total case = $6!$
Favourable case = ${6}C_2 . 4! = (15)4! = (30)4!$
$P = \frac{(15)4!}{(30)4!} = \frac{1}{2}$
Probability when not in order = $1 - \frac{1}{2} = \frac{1}{2}$
#990
Mathematics
Statistics and Probability
MCQ_SINGLE
APPLY
EASY
2025
JEE Main 2025 (Online) 28th January Evening Shift
KNOWLEDGE
4 Marks
Bag $B_1$ contains 6 white and 4 blue balls, Bag $B_2$ contains 4 white and 6 blue balls, and Bag $B_3$ contains 5 white and 5 blue balls. One of the bags is selected at random and a ball is drawn from it. If the ball is white, then the probability that the ball is drawn from Bag $B_2$ is:
(A) $\frac{2}{5}$
(B) $\frac{4}{15}$
(C) $\frac{1}{3}$
(D) $\frac{2}{3}$
Key: B
Sol:
Sol:
$E_1$: Bag $B_1$ is selected
$B_1$: 6 W 4 B
$B_2$: 4 W 6 B
$B_3$: 5 W 5 B
$E_2$: bag $B_2$ is selected
We have to find $P(\frac{E_2}{A})$
$P(\frac{E_2}{A}) = \frac{P(E_2)P(\frac{A}{E_2})}{P(E_1)P(\frac{A}{E_1}) + P(E_2)P(\frac{A}{E_2}) + P(E_3)P(\frac{A}{E_3})} = \frac{\frac{1}{3} \times \frac{4}{10}}{\frac{1}{3} \times \frac{6}{10} + \frac{1}{3} \times \frac{4}{10} + \frac{1}{3} \times \frac{5}{10}} = \frac{4}{15}$
#989
Mathematics
Statistics and Probability
MCQ_SINGLE
APPLY
EASY
2025
JEE Main 2025 (Online) 29th January Evening Shift
KNOWLEDGE
4 Marks
Bag 1 contains 4 white balls and 5 black balls, and Bag 2 contains n white balls and 3 black balls. One ball is drawn randomly from Bag 1 and transferred to Bag 2. A ball is then drawn randomly from Bag 2. If the probability, that the ball drawn is white, is $\frac{29}{45}$, then n is equal to:
(A) 5
(B) 6
(C) 4
(D) 3
Key: B
Sol:
Sol:
Bag $1 = \{4 W, 5 B\}$
Bag $2 = \{nW, 3B\}$
$P(\frac{W}{Bag2}) = \frac{29}{45}$
$\Rightarrow P(\frac{W}{B_1}) \times P(\frac{W}{B_2}) + P(\frac{B}{B_1}) \times P(\frac{W}{B_2}) = \frac{29}{45}$
$\frac{4}{9} \times \frac{n+1}{n+4} + \frac{5}{9} \times \frac{n}{n+4} = \frac{29}{45}$
$n = 6$
#988
Mathematics
Statistics and Probability
MCQ_SINGLE
APPLY
EASY
2025
JEE Main 2025 (Online) 2nd April Evening Shift
KNOWLEDGE
4 Marks
Given three indentical bags each containing $10$ balls, whose colours are as follows:
| | Red | Blue | Green |
|--------|-----|------|-------|
| Bag I | $3$ | $2$ | $5$ |
| Bag II | $4$ | $3$ | $3$ |
| Bag III| $5$ | $1$ | $4$ |
A person chooses a bag at random and takes out a ball. If the ball is Red, the probability that it is from bag I is $p$ and if the ball is Green, the probability that it is from bag III is $q$, then the value of $(\frac{1}{p} + \frac{1}{q})$ is:
| | Red | Blue | Green |
|--------|-----|------|-------|
| Bag I | $3$ | $2$ | $5$ |
| Bag II | $4$ | $3$ | $3$ |
| Bag III| $5$ | $1$ | $4$ |
A person chooses a bag at random and takes out a ball. If the ball is Red, the probability that it is from bag I is $p$ and if the ball is Green, the probability that it is from bag III is $q$, then the value of $(\frac{1}{p} + \frac{1}{q})$ is:
(A) $6$
(B) $9$
(C) $7$
(D) $8$
Key: C
Sol:
Sol:
Probability that a Red ball comes from Bag I ($p$):
$p(B_1/R) = \frac{p(B_1) \cdot p(R/B_1)}{p(R)}$
Substituting the values,
$p(B_1/R) = \frac{\frac{1}{3} \times \frac{3}{10}}{\frac{1}{3} \times \frac{3}{10} + \frac{1}{3} \times \frac{4}{10} + \frac{1}{3} \times \frac{5}{10}}$
Simplify to find $p$:
$=\frac{\frac{1}{10}}{\frac{1}{3}(1.2)} = \frac{1}{4}$
So, $p = \frac{1}{4}$.
Probability that a Green ball comes from Bag III ($q$):
$p(B_3/G) = \frac{p(B_3) \cdot p(G/B_3)}{p(G)}$
Substitute the values,
$p(B_3/G) = \frac{\frac{1}{3} \times \frac{4}{10}}{\frac{1}{3} \times \frac{5}{10} + \frac{1}{3} \times \frac{3}{10} + \frac{1}{3} \times \frac{4}{10}}$
Simplify to find $q$:
$=\frac{\frac{2}{15}}{\frac{1}{3} \times 1.2} = \frac{1}{3}$
So, $q = \frac{1}{3}$.
Calculation of $(\frac{1}{p} + \frac{1}{q})$:
$\frac{1}{p} = 4$, $\frac{1}{q} = 3$
Therefore,
$(\frac{1}{p} + \frac{1}{q}) = 4 + 3 = 7$
#716
Mathematics
Practice
MCQ_SINGLE
APPLY
MEDIUM
2023
KNOWLEDGE
4 Marks
The number of real solutions of the equation x^2 + 5|x| + 6 = 0 is:
Key: 0
Sol:
Sol:
Since |x| is always non-negative, x^2 + 5|x| + 6 is the sum of positive terms plus 6, which can never be zero. Thus, no real solution.
#714
Mathematics
Practice
MCQ_SINGLE
APPLY
MEDIUM
2021
KNOWLEDGE
4 Marks
A block of mass m is placed on a smooth wedge of inclination θ. The whole system is accelerated horizontally so that the block does not slip. The acceleration is:
Key: g tan θ
Sol:
Sol:
For the block to remain stationary relative to the wedge, the pseudo force ma must balance the component of gravity along the incline. ma cosθ = mg sinθ => a = g tanθ.
#713
Mathematics
Practice
MCQ_MULTI
REMEMBER
EASY
2022
KNOWLEDGE
4 Marks
Which of the following ores contain Iron?
Key: Haematite, Magnetite
Sol:
Sol:
Haematite is Fe2O3 and Magnetite is Fe3O4. Bauxite is Al, Malachite is Cu.
#712
Mathematics
Practice
MCQ_SINGLE
APPLY
MEDIUM
2023
KNOWLEDGE
4 Marks
If the complex number z satisfies |z| = 1 and z ≠ -1, then z/(1+z^2) is purely:
Key: Real
Sol:
Sol:
Let z = e^(iθ). Then z/(1+z^2) = e^(iθ) / (1 + e^(2iθ)). Simplifying this using Euler formula results in a real number.
#708
Mathematics
Practice
MCQ_MULTI
REMEMBER
EASY
2022
KNOWLEDGE
4 Marks
Which of the following compounds show Hydrogen bonding?
Key: A, C
Sol:
Sol:
Hydrogen bonding occurs when H is bonded to highly electronegative atoms like F, O, or N.
#707
Mathematics
Practice
MCQ_SINGLE
APPLY
MEDIUM
2023
KNOWLEDGE
4 Marks
A particle moves along a straight line such that its displacement x changes with time t as x = t^3 - 6t^2 + 3t + 4. What is the velocity when acceleration is zero?
Key: -9 m/s
Sol:
Sol:
Velocity v = dx/dt = 3t^2 - 12t + 3. Acceleration a = dv/dt = 6t - 12. For a=0, 6t=12 => t=2s. At t=2, v = 3(4) - 12(2) + 3 = -9.
#705
Mathematics
Statistics and Probability