NDA Mathematics 18 April 2021
Paper was held on Sun, Apr 18, 2021 8:30 AM
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Mathematics

What is C(n, 1) + C(n, 2) + _ _ _ _  _ + C(n, n) equal to
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What is the sum of the coefficients of first and last terms in the expansion of (1 + x)2n, where n is a natural number?
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If the first term of an AP is 2 and the sum of the first five terms is equal to one-fourth of the sum of the next five t
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Consider the following statements: 1. If each term of a GP is multiplied by same non-zero number, then the resulting se
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How many 5-digit prime numbers can be formed using the digits 1, 2, 3, 4, 5 if the repetition of digits is not allowed?
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If f(x + 1) = x2 - 3x + 2, then what is f(x) equal to?
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If x2, x, -8 are in AP, then which one of the following is correct?
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The third term of a GP is 3. What is the product of its first five terms?
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The element in the ith row and the jth column of a determinant of third order is equal to 2(i + j). What is the value of
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With the numbers 2, 4, 6, 8, all the possible determinants with these four different elements are constructed. What is t
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What is the radius of the circle 4x2 + 4y2 - 20x + 12y - 15 = 0?
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A parallelogram has three consecutive vertices (-3, 4), (0, -4) and (5, 2). The fourth vertex is
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If the lines y + px = 1 and y - qx = 2 are perpendicular, then which one of the following is correct?
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If A, B and C are in AP, then the straight line Ax + 2By + C = 0 will always pass through a fixed point. The fixed point
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If the image of the point (-4, 2) by a line mirror is (4, -2), then what is the equation of the line mirror?
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$\rm tan^{-1}x+cot^{-1}x=\frac{\pi}{2}$ holds, when
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If $\tan A=\dfrac{1}{7}$, then what is cos 2A equal to?
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The sides of a triangle are m, n and $\rm \sqrt{m^2+n^2+mn}$. What is the sum of the acute angles of the triangle?
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What is the area of the triangle ABC with sides a = 10cm  and c = 4cm angle B = 30°?
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Consider the following statements: 1. A = {1, 3, 5} and B = {2, 4, 7} are equivalent sets. 2. A = {1, 5, 9} and B = {1
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Consider the following statements: 1. The null set is a subset of every set. 2. Every set is a subset of itself. 3. I
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Let R be a relation defined as xRy if and only if 2x + 3y = 20, where x, y ∈ N. How many elements of the form (x, y
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Consider the following statements: 1. A function f : Z → Z, defined by f(x) = x + 1, is one-one as well as onto.
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Consider the following in respect of a complex number z: 1. $\rm {\overline{\left(z^{-1}\right)}}=(\bar{z})^{-1}$
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1. The difference of Z and its conjugate is an imaginary number. 2. The sum of Z and its conjugate is a real number.
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What is the modulus of the complex number i2n + 1(-i)2n - 1, where n ∈ N and i = √-1?
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If α and β are the roots of the equation 4x2 + 2x - 1 = 0, then which one of the following is correct?
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If one root of 5x2 + 26x + k = 0 is reciprocal of the other, then what is the value of k?
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In how many ways can a team of 5 players be selected from 8 players so as not to include a particular player?
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What is the coefficient of the middle term in the expansion of (1 + 4x + 4x2)5?
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If $\rm tan\:x=-\dfrac{3}{4}$ and x is in the second quadrant, then what is the value of sin x ⋅ cos x?
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What is the value of the following? $\rm cosec\left(\dfrac{7\pi}{6}\right)sec\left(\dfrac{5\pi}{3}\right)$
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If the determinant $\left| {\begin{array}{*{20}{c}} x&1&3\\ 0&0&1\\ 1&x&4 \end{array}} \rig
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What is the value of the following? tan 31° tan 33° tan 35° _ _ _ _ _ tan 57° tan 59°
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If  $f(x)=\left|\begin{array}{ccc}1 & 1 & x+1 \\ 2 x & x(x-1) & x(x+1) \\ 3 x(x-1) & 2(x-1)(x-2) & x(x+1)(x-1)\end{
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The equation $sin^{-1}x-cos^{-1}x=\frac{\pi}{6}$ has
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What is the value of the following? (sin 24° + cos 66°)(sin 24° - cos 66°)
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A chord subtends an angle 120° at the centre of a unit circle. What is the length of the chord?
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What is (1 + cot θ - cosec θ)(1 + tan θ + sec θ) equal to?
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What is $\rm \frac{1+tan^2\theta}{1+cot^2\theta}-\left(\frac{1-tan\theta}{1-cot\theta}\right)^2$equal to?  
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What is the interior angle of a regular octagon of side length 2 cm?
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If 7 sinθ + 24 cosθ = 25, then what is the value of (sin θ + cos θ)?
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A ladder 6 m long reaches a point 6 m below the top of a vertical flagstaff. From the foot of the ladder, the elevation
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The shadow of a tower is found to be x meter longer, when the angle of elevation of the sun changes from 60° to 45°. If
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If 3cosθ = 4sinθ, then what is the value of tan (45° + θ)?
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The smallest positive integer n for which $\rm \left(\frac{1-i}{1+i}\right)^{n^2}=1$ where i = √-1, is
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The value of x, satisfying the equation  $log_{cos x} ~sin x = 1$, where $0<x<\dfrac{\pi}{2}$, is
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If Δ is the value of the determinant $\left| {\begin{array}{*{20}{c}} {{a_1}}&{{b_1}}&{{c_1}}\\ {{a_2}}&am
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If C0, C1, C2, _ _ _ _ _, Cn are the coefficients in the expansion of (1 + x)n, then what is the value of C1 + C2 + C3 +
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If a + b + c = 4 and ab + bc + ca = 0, then what is the value of the following determinant? $\left| {\begin{array}{*{20
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The number of integer values of k, for which the equation 2sinx = 2k + 1 has a solution, is
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If a1, a2, a3, _ _ _ _ _, a9 are in GP, then what is the value of the following determinant? $\left| {\begin{array}{*{2
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If the roots of the quadratic equation x2 + 2x + k = 0 are real, then
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If n = 100!, then what is the value of the following? $\rm \dfrac{1}{log_2n}+\dfrac{1}{log_3n}+\dfrac{1}{log_4n}+{.....
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If Z = 1 + i, where i = √-1, then what is the modulus of $\rm z+\frac{2}{z}?$
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If A and B are two matrices such that AB is of order n × n, then which one of the following is correct?
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How many matrices of different orders are possible with elements comprising all prime numbers less than 30?
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Let $A = \left| {\begin{array}{*{20}{c}} p&q\\ r&s \end{array}} \right|$ where p, q, r and s are any four
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If A and B are square matrices of order 2 such that det(AB) = det(BA), then which one of the following is correct?
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What is cot 2x cot 4x - cot 4x cot 6x - cot 6x cot 2x equal to
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If M is the mean of n observations x1 - k, x2 - k, x3 - k, _ _ _, xn - k, where k is any real number, then what is the m
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What is the sum of deviations of the variate values 73, 85, 92, 105, 120 from their mean?
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Let x be the HM and y be the GM of two positive numbers m and n. If 5x = 4y, then which one of the following is correct?
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If the mean of a frequency distribution is 100 and the coefficient of variation is 45%, then what is the value of the va
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Let two events A and B be such that P(A) = L and P(B) = M. Which one of the following is correct?
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For which of the following sets of numbers do the mean, median and mode have the same value?
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The mean of 12 observations is 75. If two observation are discarded, then the mean of the remaining observations is 65.
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If k is one of the roots of the equation x(x + 1) + 1 = 0, then what is its other root?
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The geometric mean of a set of observations is computed as 10. The geometric mean obtained when each observations xi is
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If $\rm P(A\cup B)=\dfrac{5}{6}, P(A\cap B)=\dfrac{1}{3}\:and\:P(\bar A)=\dfrac{1}{2}$, then which of the following
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The average of a set of 15 observations is recorded, but later it is found that for one observation, the digit in the te
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A coin is tossed twice. If E and F denote occurrence of head on first toss and second toss respectively, then what is P(
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In a binomial distribution, the mean is $\dfrac{2}{3}$ and variance is $\dfrac{5}{9}$. What is the probability that
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If the mode of the scores 10, 12, 13, 15, 15, 13, 12, 10, x is 15, then what is the value of x?
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If A and B are two events such that $\rm P(A)=\dfrac{3}{4} \:and\: P(B)=\dfrac{5}{8}$, then consider the following
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What is the derivative of ex with respect to xe?
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If a differentiable function f(x) satisfies $\mathop {\lim }\limits_{x \to - 1} \dfrac{f(x)+1}{x^2-1}=-\dfrac{3}{2}
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If the function $\rm f\left( x \right) = \left\{ {\begin{array}{*{20}{c}} {a + bx,\;\;}&{x < 1}\\ {5,}&{
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Consider the following statements in respect of the function f(x) = sin x: 1. f(x) increases in the interval (0, π
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What is the domain of the function f(x) = 3x?
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If the general solution of a differential equation is y2 + 2cy - cx + c2 = 0, where c is an arbitrary constant, then wha
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What is the degree of the following differential equation? $\rm x=\sqrt{1+\frac{d^2y}{dx^2}}$
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Which one of the following differential equations has the general solution y = aex + be-x?
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What is the solution of the following differential equation? $\rm \ln\left(\frac{dy}{dx}\right)+y = x$
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What is $\rm \int e^{\left(2\ln x+\ln x^2\right)}dx$ equal to?
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Consider the following measures of central tendency for a set of N numbers: 1. Arithmetic mean. 2. Geometric mean. Wh
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The numbers of Science, Arts and Commerce graduates working in a company are 30, 70 and 50 respectively. If these figure
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For a histogram based on a frequency distribution with unequal class intervals, the frequency of a class should be propo
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The co-efficient of correlation is independent of:
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The following tables gives the frequency distribution of number of peas per pea pod of 198 pods: Number of
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If $\rm\mathop {\lim }\limits_{x \to a} \frac{a^x -x^a}{x^x -a^a}= - 1$, then what is the value of a?
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A particle starts from origin with a velocity (in m/s) given by the equation $\rm \frac{dx}{dt}=x+1$. The time (in secon
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What is $\rm \int_0^a \frac{f(a-x)}{f(x)+f(a-x)}\ dx $ equal to?
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What is $\rm\mathop {\lim }\limits_{x \to 2}\frac{x^3 + x^2}{x^2 + 3x + 2}$ equal to?
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If $\rm \int_0^a \left[f(x)+f(-x)\right]dx=\int_{-a}^{\ \ a} g(x)\ dx $, then what is g(x) equal to?
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What is the area bounded by $\rm y=\sqrt{16-x^2}$, y ≥ 0 and the x-axis?
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The curve y = -x3 + 3x2 + 2x - 27 has the maximum slope at:
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A 24 cm long wire is bent to form a triangle with one of the angles as 60°. What is the altitude of the triangle having
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If f(x) = e|x|, then which one of the following is correct?
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What is $\rm \int \frac{dx}{\sec x+\tan x}$ equal to?
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What is $\int \dfrac{dx}{sec^2({tan}^{-1}x)}$ equal to?
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If x + y = 20 and P = xy, then what is the maximum value of P?
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What is the derivative of sin(ln x) + cos(ln x) with respect to x at x = e?
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If x = et cost and y = et sint, then what is $\dfrac{dx}{dy}$ at t = 0 equal to?
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What is the maximum value of sin 2x ⋅ cos 2x?
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Consider the following statements in respect of the points (p, p - 3), (q + 3, q) and (6, 3): 1. The points lie on a st
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What is the acute angle between the lines x - 2 = 0 and √3x - y - 2 = 0?
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The point of intersection of diagonals of a square ABCD is at the origin and one of its vertices is at A(4, 2). What is
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If any point on a hyperbola is (3tan θ, 2sec θ), then what is the eccentricity of the hyperbola?
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Consider the following with regard to eccentricity (e) of a conic section: 1. e = 0 for circle 2. e = 1 for parabola
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What is the angle between the two lines having direction ratios (6, 3, 6) and (3, 3, 0)?
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If l, m, n are the direction cosines of the line x - 1 = 2(y + 3) = 1 - z, then what is l4 + m4 + n4 equal to?
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What is the projection of the line segment joining A(1, 7, -5) and B(-3, 4, -2) on y-axis?
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What is the number of possible values of k for which the line joining the points (k, 1, 3) and (1, -2, k + 1) also passe
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The foot of the perpendicular drawn from the origin to the plane x + y + z = 3 is
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A vector $\vec r=a \hat i+b \hat j$ is equally inclined to both x and y axes. If the magnitude of the vector is 2 u
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Consider the following statements in respect of a vector $\vec c=\vec a+\vec b$, where $|\vec a|=|\vec b|\ne0$: 1.&nbsp
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If $\vec a \:and\: \vec b$ are two vectors such that $|\vec a + \vec b|= |\vec a - \vec b|=4,$ then which one
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If $\vec a, \vec b\:and \: \vec c$ are coplanar, then what is $(2\vec a\times 3\vec b)\cdot4\vec c+(5\vec b\ti
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Consider the following statements: 1. The cross product of two unit vectors is always a unit vector. 2. The dot produc
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