Nimcet 2020 Solution
NIMCET 2020 PAPER AND SOLUTIONS
Questions 01: If \(\left( {\begin{array}{*{20}{c}}{15}\\8\end{array}} \right) + \left( {\begin{array}{*{20}{c}}{15}\\7\end{array}} \right) = \left( {\begin{array}{*{20}{c}}n\\r\end{array}} \right)\), then the values of \(n\) and \(r\) are:
(B) 16 and 8
(C) 16 and 9
(D) 30 and 15
We know the formula that \(\left( {\begin{array}{*{20}{c}}m\\k\end{array}} \right) + \left( {\begin{array}{*{20}{c}}m\\{k + 1}\end{array}} \right) = \left( {\begin{array}{*{20}{c}}{m + 1}\\{k + 1}\end{array}} \right)\),
Here \(m\) = 15 and \(k\) = 7, hence the desired sum is \(\left( {\begin{array}{*{20}{c}}{16}\\8\end{array}} \right)\)
Thus \(n\) = 16 and \(r\) = 8.
Questions 02: In a class of 50 students, it was found that 30 students read “Hitavad”, 35 students read “Hindustan” and 10 read neither. How many students read both: “Hitavad” and “Hindustan” newspapers?
(B) 20
(C) 15
(D) 30
Suppose number of students reading Hidavat and Hindustan are \(n(A)\) and \(n(B)\), then
\(n(A \cup B) = n(A) + n(B) - n(A \cap B)\)
\( \Rightarrow 50 - 10 = 30 + 35 - n(A \cap B)\)
\( \Rightarrow n(A \cap B) = 25\)
Questions 03: If \(A = \{ {4^x} - x - 1:x \in \mathbb{N}\} \) and \(B = \{ 9(x - 1):x \in \mathbb{N}\} \), where \(\mathbb{N}\) is the set of natural numbers, then
(B) A ⊆ B
(C) A ⊃ B
(D) A ⊇ B
Given that A = \({4^x} - 3x - 1\) and B = 9(x – 1)
By putting x = 1, 2, 3, 4… we see that,
A = {0, 9, 54, …} and B = {0, 9, 18, 27, …}
The set A is a proper subset of B or \(A \subset B\)
Alternately we can expand A as
\({(1 + 3)^x} - 3x - 1\)
\( = 1 + 3x + {\,^x}{{\rm{C}}_2} \cdot {3^2} + .... - 3x - 1\)
= a multiple of 9.
Here A and B are both multiple of 9, but B contains each multiple of 9 while A does not. Thus A is a subset of B.
Questions 04: If \(A= \{x, y, z\}\), then the number of subsets in power set of \(A\) is:
Questions 05: How many words can be formed starting with letter D taking all letters from word DELHI so that the letters are not repeated:
In DELHI all the letters are different. The first letter is fixed, so the remaining 4 letters can be permuted in 4! ways.
Number of such words = 4! = 24.
Questions 06: Naresh has 10 friends, and he wants to invite 6 of them to a party. How many times will 3 particular friends never attend the party?
Out of the 10 friends, 3 are not attending the party, so Naresh has to select 6 friends out of 7 friends.
Number of ways = \(^7{{\rm{C}}_6} = 7\)
Questions 07: There is a young boy’s birthday party in which 3 friends have attended. The mother has arranged 10 games where a prize is awarded for a winning game. The prizes are identical. If each of the 4 children receives at least one prize, then how many distributions of prizes are possible?
Total number of prizes are 10 and there are 10 recipients, number of ways is equal to the number of solutions of the equation \(x + y + z + w = 10\), where \(x,\;y,\;z,\,\,w \ge 1\).
Hence the number of solutions = \(^{10 - 1}{{\rm{C}}_{4 - 1}} = {\,^9}{{\rm{C}}_3} = 84\)
Questions 08: Three cities A, B, C are equidistant from each other. A motorist travels from A to B at 30km/hour, from B to C at 40km/hour and from C to A at 50km/hour. Then the average speed is
(B) 40km/hour
(C) 38.3km/hour
(D) 37.6km/hour
Suppose the distance AB = BC = CA = \(x\), then total journey = \(3x\) and total time taken in the journey = \(\frac{x}{{30}} + \frac{x}{{40}} + \frac{x}{{50}} = \frac{{47x}}{{600}}\).
Hence the average speed = \(\frac{{{\rm{Total}}\;\,{\rm{Journey}}}}{{{\rm{Total}}\;\,{\rm{time}}}}\)
\( = \frac{{3x}}{{\frac{{47x}}{{600}}}} = \frac{{1800}}{{47}} = 38.3\)
Questions 09: A problem in Mathematics is given to 3 students A, B and C. If the probability of A solving the problem is \(\frac{1}{2}\) and B not solving it is \(\frac{1}{4}\). The whole probability of the problem being solved is \(\frac{{63}}{{64}}\), then what is the probability of solving it by C?
(B) \(\frac{1}{{64}}\)
(C) \(\frac{7}{8}\)
(D) \(\frac{1}{2}\)
Probabilities that B will solve the problem = \(1 - \frac{1}{4} = \frac{3}{4}\). Let probability that C will solve the problem = \(p\), then probability that none of them is able to solve the problem = \(\frac{1}{2} \times \frac{1}{4} \times (1 - p) = \frac{{1 - p}}{8}\).
From the given information,
\(\frac{{1 - p}}{8} = \frac{1}{{64}} \Rightarrow p = \frac{7}{8}\)Questions 10: A and B play a game where each is asked to select a number from 1 to 25. If the two numbers match, both win a prize. The probability that they will not win a prize in a single trial is
(B) \(\frac{{24}}{{25}}\)
(C) \(\frac{2}{{25}}\)
(D) \(\frac{3}{{25}}\)
A can select any number from the first 25 numbers with probability \(\frac{{25}}{{25}}\). Now B has to select a number different from A, this can be done with probability \(\frac{{24}}{{25}}\).
Required probability = \(\frac{{24}}{{25}}\).
Questions 11: A, B, C are three sets of values of \(x\):
(A) Mean of A is equal to Mode of C.
(B) Mean of C is equal to Median of B.
(C) Median of B is equal to Mode of A.
(D) Mean, Median and Mode of A are same.
Questions 12: Standard deviation for the following distribution is:
Questions 13: If A = \(\left[ {\begin{array}{*{20}{c}}{\cos \alpha }&{\sin \alpha }\\{ - \sin \alpha }&{\cos \alpha }\end{array}} \right]\), then for any value of \(n\), the value of \(A_n\) is:
(B) \(\left[ {\begin{array}{*{20}{c}}{\cos n\alpha }&{\sin n\alpha }\\{\sin n\alpha }&{\cos n\alpha }\end{array}} \right]\)
(C) \(\left[ {\begin{array}{*{20}{c}}{\cos n\alpha }&{\sin n\alpha }\\{\sin n\alpha }&{ - \cos n\alpha }\end{array}} \right]\)
(D) \(\left[ {\begin{array}{*{20}{c}}{\cos n\alpha }&{\sin n\alpha }\\{ - \sin n\alpha }&{\cos n\alpha }\end{array}} \right]\)
Questions 14: Roots of equation \(a{x^2}-2bx + c = 0\) are \(n\) and \(m\), then the value of \(\frac{b}{{a{n^2} + c}} + \frac{b}{{a{m^2} + c}}\) is:
(B) \(\frac{b}{a}\)
(C) \(\frac{a}{c}\)
(D) \(\frac{a}{b}\)
Questions 15: The number of values of \(k\) for which the linear equations
(B) 1
(C) 0
(D) 3
Questions 16: Let \(A = ({a_{ij}})\)and \(B = ({b_{ij}})\) be two square matrices of order \(n\) and \(\det (A)\) denotes the determinant of A. Then, which of the following is not correct?
(B) \(\det (AB) = \det (A) \cdot \det (B)\)
(C) \(\det (cA) = c\det (A)\)
(D) \(\det (A) = \det ({A^T})\), where \({A^T}\) denotes the transpose of the matrix A.
Questions 17: The tangent to the ellipse \(x^2 + 16y^2 = 16\) and making 60° angle with positive \(x\) axis is:
(A) x – √3 y + 7 = 0
(B) √3 x – y + 8 = 0
(C) √3 x – y + 7 = 0
(D) x + √3y + 7 = 0
The equation of the ellipse is \(\frac{{{x^2}}}{{16}} + \frac{{{y^2}}}{1} = 1\) and the slope of the tangent = \(\tan 60 = \sqrt 3 \).
If the equation of the tangent is \(y = mx + c\), then \({c^2} = {a^2}{m^2} + {b^2}\)
\( \Rightarrow {c^2} = 16 \times 3 + 1 = 49\)
Or \(c = \pm 7\)
Equation of the tangent is \(y = \sqrt 3 x \pm 7\)
Questions 18: Find the number of point(s) of intersection of the ellipse \(\frac{{{x^2}}}{4} + \frac{{{{(y - 1)}^2}}}{9} = 1\) and the circle \({x^2} + {y^2} = 4\).
Questions 19: An arithmetic progression has 3 as its first term. Also, the sum of the first 8 terms is twice the sum of the first 5 terms. Then what is the common difference?
Questions 20: If \(a + b + c = 0\), then the value of \(\frac{{{a^2}}}{{bc}} + \frac{{{b^2}}}{{ac}} + \frac{{{c^2}}}{{ac}}\) is:
Questions 21: Find \(\mathop {\lim }\limits_{x \to 0} \,\,\left( {{x^2}{e^{\sin \frac{1}{x}}}} \right)\)
(B) limit does not exist
(C) infinity
(D) None of these
Questions 22: If \(f(x) = \left\{ {\;\begin{array}{*{20}{c}}{{x^2}}&{x \le 0}\\{2\sin x}&{x > 0}\end{array}} \right.\), then \(x = 0\) is:
(B) Point of maxima
(C) Point of discontinuity
(D) None of these
Questions 23: If \(g(x) = \left\{ {\begin{array}{*{20}{c}}{\frac{{{x^2} - 2x}}{{2x}}}&{x \ne 0}\\k&{x = 0}\end{array}} \right.\) is a continuous function at \(x = 0\), then the value of \(k\) is :
(B) 1/2
(C) 1
(D) None of these
The value of the function\(g(x)\) when \(x \ne 0\) is \(\frac{x}{2} - \frac{1}{2}\).
When \(x = 0 + h\) or \(x = 0 - h\), then \(g(x) = - \frac{1}{2}\).
As the function is continuous, so \(k = - \frac{1}{2}\).
Questions 24: Find the interval(s) on which the graph \(y = 2{x^3}{e^x}\) is increasing:
(B) (– 3/2, 0) and (0, ∞)
(C) (– 3, ∞) only
(D) None of these
Questions 25: If \(\int {{{\sec }^2}x\,\,{\rm{cose}}{{\rm{c}}^4}x} \,dx\) = \( - \frac{1}{3}{\cot ^3}x + k\tan x - 2\cot x + c\), then the value of \(k\) is:
(A) 1
(B) 2
(C) 3
(D) 4
Questions 26: Evaluate \(\int {{e^x}} \left( {\frac{{1 + \sin x\cos x}}{{{{\cos }^2}x}}} \right)dx\)
(A) \({e^x}\cos x + c\)
(B) \({e^x}\sec x\tan x + c\)
(C) \({e^x}\tan x + c\)
(D) \({e^x}{\cos ^2}x - 1 + c\)
Questions 27: If \({I_n} = \int\limits_0^a {({x^2} - {y^2})\,dx} \), where \(n\) is a positive integer, then the relation between \({I_n}\) and \({I_{n - 1}}\) is
(B) \({I_n} = \frac{{2n^2{a^2}}}{{2n - 1}}{I_{n - 1}}\)
(C) \({I_n} = \frac{{2n{a^2}}}{{2n - 1}}{I_{n - 1}}\)
(D) \({I_n} = \frac{{2n^2{a^2}}}{{2n+ 1}}{I_{n - 1}}\)
Questions 28: The value of \(\int\limits_{ - 2}^2 {(a{x^5} + b{x^3} + c)} \,dx\) depends on the
(B) Value of \(c\)
(C) Value of \(a\)
(D) Value of \(a\) and \(b\)
Questions 29: Find the area bounded by the line \(y = 3 - x\), the parabola \(y = {x^2} - 9\) and \(x \ge - 1\), \(y \ge 0\).
(B) 11/2
(C) 9/2
(D) None of these
Questions 30: If \(\vec a,\vec b,\vec c\) are three non-coplanar vectors, then \((\vec a + \vec b + \vec c).\left[ {\left( {\vec a + \vec b} \right) \times \left( {\vec a + \vec c} \right)} \right]\)
(B) \(\left[ {\vec a\;\vec b\;\vec c} \right]\)
(C) \(2\left[ {\vec a\;\vec b\;\vec c} \right]\)
(D) \(\left[ {\vec a\;\vec b\;\vec c} \right]\)
Questions 31: Two forces \({F_1}\) and \({F_2}\) are used to pull a car, which met an accident. The angle between the two forces is \(\theta \). Find the values of \(\theta \) for which the resultant force is equal to:
(A) \(\theta = 0\)
(B) \(\theta = 45\)
(C) \(\theta = 90\)
(D) \(\theta = 135\)
Questions 32: If \(\vec a,\vec b,\vec c,\vec d\;\) are four vectors such that \(\vec a + \vec b + \vec c\;\;\)Is collinear with \(\vec d\) and \(\vec b + \vec c + \;\vec d\;\) is collinear with \(\vec a,\) then \(\vec a + \vec b + \vec c + \vec d\;\) is
(B) collinear with \(\vec a + \vec d\;\)
(C) collinear with \(\vec a - \vec d\)
(D) collinear with \(\vec b - \vec c\)
Questions 33: Forces of magnitude 5, 3, 1 units act in the directions 6i + 2j + 3k, 3i – 2j + 6k, 2i – 3j – 6k respectively on a particle which is displaced from the point (2, – 1, – 3) to (5, – 1, 1). The total work done by the force is
(B) 5 units
(C) 33 units
(D) 105 units
Questions 34: The position vectors of points A and B are \(\vec a\) and \(\vec b\) . Then the position vector of point P dividing AB in the ratio \(m:n\) is
(B) \(\frac{{n\vec a + m\vec b}}{{m - n}}\)
(C) \(\frac{{n\vec a - m\vec b}}{{m + n}}\)
(D) None of these
Questions 35: If \(\vec a,\vec b,\vec c\;\) are three non-zero vectors with no two of which are \(\vec a + 2\vec b\;\;\)is collinear with \(\vec c\) and \(\vec b + \overrightarrow {3c} \;\) is collinear with \(\vec a,\) then \(\left| {\vec a + 2\vec b + 6\vec c} \right|\) will be equal to
(B) 9
(C) 1
(D) None of above
Questions 36: Vertices of the vectors i – 2j + 2k, 2i + j – k and 3i – j + 2k form a triangle. This triangle is
(B) Right angle triangle
(C) Two sides are equal in length
(D) None of the above
Questions 37: If the volume of a parallelepiped whose adjacent edges are \(\vec a = 2i + 3j + 4k,\)\(\vec b = i + \alpha j + 2k,\) is 15, then \(\alpha \) is:
(B) 5/2
(C) 9/2
(D) 0
Questions 38: Solve the equation \({\sin ^2}x - \sin x - 2 = 0\) for \(x\) on the interval \(0 \le x \le 2\pi \)
(B) \(x = \frac{\pi }{4}\;\;{\rm{and}}\;\frac{{2\pi }}{7}\)
(C) \(x = \frac{{2\pi }}{3}\;\;{\rm{and}}\;\frac{{2\pi }}{5}\)
(D) None of these
Questions 39: If \(\frac{{\tan x}}{2} = \frac{{\tan y}}{3} = \frac{{\tan z}}{5}\;\)and \(x + y + z = \pi \), then the value of \({\tan ^2}x + {\tan ^2}y + {\tan ^2}z\)
(B) 38
(C) 114
(D) None of these
Questions 40: Find the value of sin 12°sin 48°sin 54°:
(B) 1/6
(C) 1/2
(D) 1/4
Questions 41: If cos x = tan y, cot y = tan z and cot z = tan x, then sin x is:
(B) \(\frac{{\sqrt 5 - 1}}{2}\)
(C) \(\frac{{\sqrt 5 + 1}}{4}\)
(D) \(\frac{{\sqrt 5 - 1}}{4}\)
Questions 42: The value of \(\tan \left( {45 + \frac{A}{2}} \right)\) is
(B) cot θ + sec θ
(C) tan θ – sec θ
(D) tan θ + sec θ
Questions 43: The value of sin 10° sin 50° sin 70° is :
(B) 1/2
(C) 3/4
(D) 1/8
Questions 44: The expression \(\frac{{\tan A}}{{1 - \cot A}} + \frac{{\cot A}}{{1 - \tan A}}\) can be written as
(B) sec A cosec A + 1
(C) tan A + cot A
(D) sec A + cosec A
Questions 45: Angle of elevation of the top of the tower from 3 points (collinear) A, B and C on a road leading to the foot of the tower are 30°, 45° and 60°, respectively. The ratio of AB and BC is
(B) \(\sqrt 3 :2\)
(C) \(1:2\)
(D) \(2:\sqrt 3 \)
Questions 46: The area enclosed between the curves \({y^2} = x\) and \(y = \left| x \right|\) is
(B) 1 sq. unit
(C) 1/6 sq. unit
(D) 1/3 sq. Unit
Questions 47: Test the continuity of the function at \(x = 2\)
(B) Discontinuous at \(x = 2\)
(C) Semi continuous at \(x = 2\)
(D) None of the above
Questions 48: The value of \(2{\tan ^{ - 1}}\left[ {{\rm{cosec}}({{\tan }^{ - 1}}x) - \tan ({{\cot }^{ - 1}}x)} \right]\) is:
(B) cotx
(C) tan⁻¹x
(D) cosec⁻¹x
Questions 49: If \(3\sin x + 4\cos x = 5\), then \(6\tan \frac{x}{2} - 9{\tan ^2}\frac{x}{2}\) is:
(B) 3
(C) 4
(D) 6
Questions 50: If A is a subset of B and B is a subset of C, then cardinality of \({\rm{A}} \cup {\rm{B}} \cup {\rm{C}}\) is equal to:
(B) Cardinality of B
(C) Cardinality of A
(D) None of the above