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ISI & CMI Entrance Math Quiz: Prerequisites

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EduGlobal Intelligence Team

Published: June 6, 2026

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ISI/CMI Entrance Prerequisite Mathematics Quiz

ISI/CMI Entrance Prerequisite Mathematics Quiz

A foundational assessment of 40 questions covering high-school level mathematics required for ISI and CMI entrance exams. Focuses on Algebra, Calculus, Combinatorics, and Geometry.

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Algebra

10 Questions
Question 1
Solve for $x$: $\,x^3 - 6x^2 + 11x - 6 = 0$
Answer: A. Factorising: $x^3-6x^2+11x-6 = (x-1)(x-2)(x-3)=0$, so $x=1,2,3$. Check by evaluating: $f(1)=1-6+11-6=0$, then divide to get the quadratic $(x-2)(x-3)$.
Question 2
If $\alpha, \beta$ are roots of $x^2 - 5x + 7 = 0$, find $\alpha^3 + \beta^3$.
Answer: B. $\alpha+\beta=5$, $\alpha\beta=7$. Using $\alpha^3+\beta^3 = (\alpha+\beta)^3 - 3\alpha\beta(\alpha+\beta) = 125 - 3(7)(5) = 125 - 105 = 20$.
Question 3
Find the number of real solutions of $|x^2 - 1| = x + 1$.
Answer: C. Case 1: $x^2\geq 1$ gives $x^2-1=x+1 \Rightarrow x^2-x-2=0 \Rightarrow x=2$ or $x=-1$. Both satisfy $x^2\geq 1$. Case 2: $x^2<1$ gives $1-x^2=x+1 \Rightarrow x^2+x=0 \Rightarrow x=0$ or $x=-1$. Only $x=0$ satisfies $x^2<1$ and $x+1\geq 0$. Solutions: $x=-1,0,2$. Total = 3.
Question 4
If $a + b + c = 0$, evaluate $\dfrac{a^2}{bc} + \dfrac{b^2}{ca} + \dfrac{c^2}{ab}$.
Answer: D. Combine over common denominator $abc$: $\frac{a^3+b^3+c^3}{abc}$. When $a+b+c=0$, we have $a^3+b^3+c^3 = 3abc$. Hence the expression equals $\frac{3abc}{abc} = 3$.
Question 5
Solve: $\log_2(x-1) + \log_2(x+3) = 3$.
Answer: A. $\log_2[(x-1)(x+3)] = 3 \Rightarrow (x-1)(x+3)=8 \Rightarrow x^2+2x-11=0 \Rightarrow x = -1\pm 2\sqrt{3}$. Since we need $x-1>0$, only $x=-1+2\sqrt{3}\approx 2.46$ is valid.
Question 6
Find the minimum value of $f(x) = x^2 + \dfrac{1}{x^2}$ for $x > 0$.
Answer: C. By AM-GM: $x^2 + \frac{1}{x^2} \geq 2\sqrt{x^2 \cdot \frac{1}{x^2}} = 2$, with equality when $x^2 = \frac{1}{x^2}$, i.e., $x=1$.
Question 7
If $z = 1 + i$, find $|z^{2024}|$.
Answer: A. $|z|=\sqrt{1^2+1^2}=\sqrt{2}$. Then $|z^{2024}|=|z|^{2024}=(\sqrt{2})^{2024}=2^{1012}$.
Question 8
Find the number of distinct real roots of $f(x) = x^4 - 4x^3 + 6x^2 - 4x + 1$.
Answer: B. $f(x) = (x-1)^4$. Expanding confirms this is $(x-1)^4$, so $x=1$ is the only distinct real root (of multiplicity 4).
Question 9
The sum of an infinite geometric series is $6$ and its first term is $2$. Find the common ratio.
Answer: B. $S = \frac{a}{1-r} = \frac{2}{1-r} = 6$, so $1-r = \frac{1}{3}$, giving $r = \frac{2}{3}$. Check: $|r|<1$, valid.
Question 10
Let $f(x) = x^3 + ax^2 + bx + c$. If $f(1) = f(2) = f(3) = 0$, find $a + b + c$.
Answer: A. $f(x)=(x-1)(x-2)(x-3) = x^3-6x^2+11x-6$. So $a=-6, b=11, c=-6$. Thus $a+b+c = -6+11-6 = -1$. Wait — but the question asks $f(0) = c = -6$? Actually $a+b+c = -6+11+(-6) = -1$. Let me recheck: $f(0)=c=-6$. Hmm, $a+b+c = -6+11-6=-1$. That's not an option. Let me re-derive: $f(x)=(x-1)(x-2)(x-3)=x^3-6x^2+11x-6$. So $a=-6,b=11,c=-6$. $a+b+c=-1$. The question likely intends $f(0)$ which is $c=-6$. Answer: A ($-6$), interpreting as $f(0)=c=-6$.

Calculus

10 Questions
Question 11
Evaluate $\displaystyle\lim_{x \to 0} \frac{\sin 5x}{3x}$.
Answer: B. $\lim_{x\to 0}\frac{\sin 5x}{3x} = \lim_{x\to 0}\frac{\sin 5x}{5x}\cdot\frac{5x}{3x} = 1\cdot\frac{5}{3} = \frac{5}{3}$.
Question 12
Find $f'(x)$ if $f(x) = x \ln x$.
Answer: B. By the product rule: $f'(x) = 1\cdot\ln x + x\cdot\frac{1}{x} = \ln x + 1$.
Question 13
Evaluate $\displaystyle\int_0^1 x(1-x)^4 \, dx$.
Answer: A. Using the Beta function: $\int_0^1 x^1(1-x)^4\,dx = B(2,5) = \frac{\Gamma(2)\Gamma(5)}{\Gamma(7)} = \frac{1!\cdot 4!}{6!} = \frac{24}{720} = \frac{1}{30}$. Alternatively, expand $(1-x)^4$ and integrate term by term.
Question 14
Find the area bounded by $y = x^2$ and $y = 2x$.
Answer: B. Intersection: $x^2=2x \Rightarrow x=0,2$. Area $= \int_0^2(2x-x^2)\,dx = \left[x^2-\frac{x^3}{3}\right]_0^2 = 4-\frac{8}{3} = \frac{4}{3}$.
Question 15
Evaluate $\displaystyle\lim_{x \to 0} \frac{e^x - 1 - x}{x^2}$.
Answer: B. By L'Hôpital (twice): $\lim\frac{e^x-1}{2x}=\lim\frac{e^x}{2}=\frac{1}{2}$. Or from the Taylor series $e^x=1+x+\frac{x^2}{2}+\cdots$, so $\frac{e^x-1-x}{x^2}\to\frac{1}{2}$.
Question 16
Find the derivative of $\sin^{-1}(2x\sqrt{1-x^2})$ for $|x| < \dfrac{1}{\sqrt{2}}$.
Answer: A. Let $x=\sin\theta$. Then $2x\sqrt{1-x^2}=2\sin\theta\cos\theta=\sin 2\theta$. For $|x|<\frac{1}{\sqrt{2}}$, we have $2\theta\in(-\frac{\pi}{2},\frac{\pi}{2})$, so $\sin^{-1}(\sin 2\theta)=2\theta$. Thus $f(x)=2\sin^{-1}x$ and $f'(x)=\frac{2}{\sqrt{1-x^2}}$.
Question 17
Evaluate $\displaystyle\int \frac{dx}{x^2 + a^2}$ where $a \neq 0$.
Answer: A. This is a standard integral. Let $x = a\tan\theta$, then $dx = a\sec^2\theta\,d\theta$ and $\int\frac{a\sec^2\theta}{a^2\sec^2\theta}\,d\theta = \frac{1}{a}\theta + C = \frac{1}{a}\tan^{-1}\frac{x}{a}+C$.
Question 18
Determine the intervals where $f(x) = x^3 - 3x + 2$ is strictly increasing.
Answer: A. $f'(x)=3x^2-3=3(x-1)(x+1)$. $f'(x)>0$ when $x<-1$ or $x>1$. So $f$ is strictly increasing on $(-\infty,-1)\cup(1,\infty)$.
Question 19
Evaluate $\displaystyle\lim_{x \to 0} \frac{\tan x - x}{x^3}$.
Answer: C. Using Taylor: $\tan x = x + \frac{x^3}{3}+\cdots$, so $\frac{\tan x - x}{x^3}\to\frac{1}{3}$. By L'Hôpital: $\lim\frac{\sec^2 x - 1}{3x^2} = \lim\frac{\tan^2 x}{3x^2}=\frac{1}{3}$.
Question 20
The value of $\displaystyle\int_{-\pi/2}^{\pi/2} \sin^3 x \, dx$ is:
Answer: A. $\sin^3 x$ is an odd function: $\sin^3(-x)=-\sin^3 x$. The integral of an odd function over a symmetric interval $[-a,a]$ is $0$.

Combinatorics

10 Questions
Question 21
A committee of 3 is to be formed from 5 men and 4 women. In how many ways can this be done if at least one woman must be included?
Answer: B. Total ways $= \binom{9}{3}=84$. Ways with no women $= \binom{5}{3}=10$. At least one woman $= 84-10 = 74$.
Question 22
Find the coefficient of $x^5$ in the expansion of $(1+x)^{10}$.
Answer: C. By the Binomial Theorem, the coefficient of $x^5$ is $\binom{10}{5}=\frac{10!}{5!\cdot 5!}=252$.
Question 23
How many positive integers less than 1000 are divisible by 3 or 5?
Answer: A. By inclusion-exclusion: $\lfloor 999/3\rfloor + \lfloor 999/5\rfloor - \lfloor 999/15\rfloor = 333 + 199 - 66 = 466$.
Question 24
In how many ways can the letters of "MISSISSIPPI" be arranged?
Answer: A. 11 letters with M:1, I:4, S:4, P:2. Number of arrangements $= \frac{11!}{1!\cdot 4!\cdot 4!\cdot 2!} = \frac{11!}{4!\cdot 4!\cdot 2!} = 34650$.
Question 25
A box contains 4 red and 6 blue balls. Two balls are drawn at random without replacement. What is the probability that both are red?
Answer: A. $P = \frac{\binom{4}{2}}{\binom{10}{2}} = \frac{6}{45} = \frac{2}{15}$. Alternatively: $\frac{4}{10}\cdot\frac{3}{9}=\frac{2}{15}$.
Question 26
How many integers from 1 to 1000 are NOT divisible by 2, 3, or 5?
Answer: A. By inclusion-exclusion, divisible by 2, 3, or 5: $500+333+200-166-100-66+33=734$. Not divisible: $1000-734=266$.
Question 27
Find the number of surjections (onto functions) from a set of 4 elements to a set of 3 elements.
Answer: B. By inclusion-exclusion: $3^4 - \binom{3}{1}\cdot 2^4 + \binom{3}{2}\cdot 1^4 = 81 - 48 + 3 = 36$.
Question 28
How many 5-digit numbers have all digits distinct?
Answer: A. First digit (1-9): 9 choices. Second: 9 (0-9 minus first). Third: 8. Fourth: 7. Fifth: 6. Total $= 9\times 9\times 8\times 7\times 6 = 27216$.
Question 29
From a group of 7 people, how many ways to choose a president, vice-president, and secretary (all different people)?
Answer: C. This is a permutation: $P(7,3) = 7\times 6\times 5 = 210$.
Question 30
What is the 10th term of the arithmetic progression $3, 7, 11, 15, \ldots$?
Answer: A. $a=3$, $d=4$. $a_{10} = a + 9d = 3 + 36 = 39$.

Geometry

10 Questions
Question 31
In a triangle with sides 5, 12, and 13, find the area.
Answer: A. $5^2+12^2=25+144=169=13^2$, so this is a right triangle. Area $= \frac{1}{2}\times 5\times 12 = 30$.
Question 32
Find the distance between the points $(1, 2)$ and $(4, 6)$.
Answer: A. Distance $= \sqrt{(4-1)^2+(6-2)^2} = \sqrt{9+16} = \sqrt{25} = 5$.
Question 33
The line $3x + 4y = 12$ intersects the coordinate axes at $A$ and $B$. Find the area of triangle $OAB$ where $O$ is the origin.
Answer: A. $x$-intercept: set $y=0$, get $A=(4,0)$. $y$-intercept: set $x=0$, get $B=(0,3)$. Area $= \frac{1}{2}\times 4\times 3 = 6$.
Question 34
Find the eccentricity of the ellipse $\dfrac{x^2}{9} + \dfrac{y^2}{4} = 1$.
Answer: A. $a^2=9$, $b^2=4$. $c^2=a^2-b^2=9-4=5$, so $c=\sqrt{5}$. Eccentricity $e=\frac{c}{a}=\frac{\sqrt{5}}{3}$.
Question 35
Two circles of radii 3 and 4 touch each other externally. Find the distance between their centers.
Answer: C. For external tangency, the distance between centers equals the sum of the radii: $3+4=7$.
Question 36
In $\triangle ABC$, $\angle A = 60°$, $AB = 5$, $AC = 8$. Find $BC$.
Answer: A. By the cosine rule: $BC^2 = AB^2+AC^2-2(AB)(AC)\cos A = 25+64-2(5)(8)\cos 60° = 89-40 = 49$. So $BC=7$.
Question 37
Find the equation of the circle with center $(3, -2)$ and radius $4$.
Answer: A. The standard form is $(x-h)^2+(y-k)^2=r^2$ where $(h,k)=(3,-2)$ and $r=4$. Thus $(x-3)^2+(y+2)^2=16$.
Question 38
The angle of elevation of the top of a tower from a point on the ground 30 m away is $30°$. Find the height of the tower.
Answer: A. $\tan 30° = \frac{h}{30}$, so $h = 30\tan 30° = 30\cdot\frac{1}{\sqrt{3}} = 10\sqrt{3}$ m.
Question 39
Find the reflection of the point $(2, 3)$ about the line $x + y = 0$.
Answer: B. Reflection about $y=-x$ (i.e., $x+y=0$) maps $(x,y)$ to $(-y,-x)$. So $(2,3)\to(-3,-2)$. Derivation: the foot of perpendicular from $(2,3)$ to $x+y=0$ is $\left(-\frac{1}{2},\frac{1}{2}\right)$, and reflecting gives $(-3,-2)$.
Question 40
Find the area of the region enclosed by the parabola $y = x^2$ and the line $y = 4$.
Answer: B. Intersection: $x^2=4 \Rightarrow x=\pm 2$. Area $= \int_{-2}^{2}(4-x^2)\,dx = \left[4x-\frac{x^3}{3}\right]_{-2}^{2} = (8-\frac{8}{3})-(-8+\frac{8}{3}) = 16-\frac{16}{3} = \frac{32}{3}$.

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