cmi-entrance

2025 mscds

11 maths questions

Q3 Composite & Inverse Functions Determine Domain or Range of a Composite Function View
3. What is the domain of the following real valued function?
$$f ( x ) = \log _ { 2 } \left( x ^ { 2 } - 5 x + 6 \right)$$
(a) $( - \infty , 2 )$
(b) $( 3 , \infty )$
(c) $( - \infty , 2 ) \cup ( 3 , \infty )$
(d) $( - \infty , \infty )$
4. Let $A = \left[ \begin{array} { l l } a & b \\ c & d \end{array} \right]$ be a real matrix which satisfies $A ^ { - 1 } = A$. Which of the following statements is/are always true?
(a) $a + d = 0$
(b) $a d - b c = 1$
(c) $a d - b c \neq 0$
(d) $a ^ { 2 } + 2 b c + d ^ { 2 } = 2$
5. Let $\mathbb { Z }$ be the set of all integers. Let $A = \left\{ n \in \mathbb { Z } \mid n ^ { 2 } + 10 n + 21 \right.$ is divisible by 7 $\}$. Which of the following statements is/are true?
(a) $A = \{ n \in \mathbb { Z } \mid ( n \equiv 0 \bmod 7 ) \}$
(b) $A = \{ n \in \mathbb { Z } \mid ( n \equiv 0 \bmod 7 )$ or $( n \equiv 4 \bmod 7 ) \}$
(c) $A = \{ n \in \mathbb { Z } \mid ( n \equiv 1 \bmod 7 )$ or $( n \equiv 5 \bmod 7 ) \}$
(d) $A = \{ n \in \mathbb { Z } \mid ( n \equiv 2 \bmod 7 )$ or $( n \equiv 6 \bmod 7 ) \}$
6. Let $n \geq 3$ be an integer, and let $x _ { 1 } , x _ { 2 } , \ldots , x _ { n }$ be variables which take real values with $0 \leq x _ { i } \leq 1$ for all $1 \leq i \leq n$. Let
$$\begin{aligned} A & = x _ { 1 } + x _ { 2 } + \ldots + x _ { n } \\ B & = x _ { 1 } x _ { 2 } + x _ { 2 } x _ { 3 } + \ldots + x _ { n - 1 } x _ { n } + x _ { n } x _ { 1 } \end{aligned}$$
Which of the following statements is/are true.
(a) $A \geq B$ is always true.
(b) $B > A$ is true for some values of the $x _ { i }$ 's and $A > B$ is true for some values of the $x _ { i }$ 's.
(c) $A = B$ has a finite number of solutions
(d) $A = B$ has an infinite number of solutions.
7. Let $B = \left( \left( b _ { i , j } \right) \right)$ be an $n \times n$ matrix. Let $p : \{ 1,2 , \ldots , n \} \mapsto \{ 1,2 , \ldots , n \}$ be a bijection (i.e. a one-to-one correspondence) and let a matrix $A = \left( \left( a _ { i , j } \right) \right)$ be defined by
$$a _ { i , j } = b _ { p ( i ) , p ( j ) } , \quad 1 \leq i , j \leq n .$$
Which of the following statement(s) is/are true for all choices of $B$ and $P$.
(a) $A$ admits an inverse if and only if $B$ admits an inverse.
(b) For any $x , y \in \mathbb { R } ^ { n } , A x = y$ admits a solution if and only if $B x = y$ admits a solution.
(c) $A$ and $B$ have the same trace.
(d) $A$ and $B$ have the same eigenvectors.
Q8 Stationary points and optimisation Find critical points and classify extrema of a given function View
8. Let $x$ be a variable that takes real values, and let $f ( x ) = x ^ { 3 } - 3 x$. Which of the following statements is/are true?
(a) $f ( x )$ has a local maximum at $x = - \sqrt { 3 }$
(b) $f ( x )$ has a local maximum at $x = - 1$
(c) $f ( x )$ has a local minimum at $x = \sqrt { 3 }$
(d) $f ( x )$ has a global minimum at $x = 1$
Q10 Combinations & Selection Counting Integer Solutions to Equations View
10. In how many ways can 10 identical chocolate bars be distributed among 5 children, in such a way that each child gets at least one chocolate bar?
(a) 50
(b) 126
(c) 252
(d) 3125
12. Let $f ( x ) = \sqrt { x }$. We draw a tangent to the curve $y = f ( x )$ at the point on the curve whose $x$ coordinate is equal to 4 . Where does this tangent intersect the $X$-axis?
(a) $x = 4$
(b) $x = - 2$
(c) $x = - 4$
(d) $x = 2$
13. Let $n$ be an integer, $n \geq 4$. $A$ is an $n \times n$ matrix with real entries. The matrix $B$ is obtained by the following sequence of operations on $A$. First, multiply each entry of $A$ by 2 . Then add 3 times the second column to the third column. Finally, swap the first and the fourth columns. If $\operatorname { det } ( A ) = 5$, which of the following statements are true?
(a) 10 divides $\operatorname { det } ( B )$
(b) $\operatorname { det } ( B ) = - 5$
(c) 100 divides $\operatorname { det } ( B )$
(d) $\operatorname { det } ( B ) = - 2 ^ { n } \cdot 5$
14. Let $x , y , z$ be positive numbers such that $x ^ { 2 } + y ^ { 2 } = z ^ { 2 }$. Determine the value of the following expression:
$$\frac { \log _ { y + z } x + \log _ { z - y } x } { \left( \log _ { y + z } x \right) \left( \log _ { z - y } x \right) }$$
(a) Undefined.
(b) $\frac { 1 } { 2 }$
(c) $\frac { 1 } { 4 }$
(d) 2
15. A game being offered in a casino consists of guessing the outcomes of two tosses of a fair coin. The gambler wins if she/he has correctly guessed at least one of the two tosses. To play a game, the gambler has to pay a fee of Rs. 80, and the winner gets a reward of Rs. 100 on winning the game (and nothing otherwise). Which of the following statements are correct?
(a) In the first 10 minutes on a given day exactly three gamblers play the game, one after the other. The probability that the casino owner makes a profit in the first 10 minutes equals $1 / 4$.
(b) One gambler plays the game three times. The probability that she wins exactly two of the three games is $27 / 64$.
(c) Three friends go together and play the game with each playing once. The probability that all three win equals $27 / 64$.
(d) If 1200 players play the game on a given day, the expected profit of the casino owner for the day equals Rs. 6000.