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CBSE Class 12 Mathematics 2024 question paper (65/3)

Maximum marks 80 · Time 3 hours · 3 sets

Try each question first, then open its model answer. Where the paper offers a choice, both questions are shown with OR between them.

Section A

1 mark each

  1. Q.11 mark
    If A=[aij]A = [a_{ij}] is an identity matrix, then which of the following is true ?

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  2. Q.21 mark
    Let R+R_+ denote the set of all non-negative real numbers. Then the function f:R+→R+f : R_+ \to R_+ defined as f(x)=x2+1f(x) = x^2 + 1 is :

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  3. Q.31 mark
    Let A=[abcd]A = \begin{bmatrix} a & b \\ c & d \end{bmatrix} be a square matrix such that adj A = A. Then, (a+b+c+d)(a + b + c + d) is equal to :

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  4. Q.41 mark
    A function f(x)=∣1−x+∣x∣∣f(x) = \left| 1 - x + |x| \right| is :

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  5. Q.51 mark
    If the sides of a square are decreasing at the rate of 1⋅51{\cdot}5 cm/s, the rate of decrease of its perimeter is :

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  6. Q.61 mark
    ∫−aaf(x) dx=0\int\limits_{-a}^{a} f(x)\, dx = 0, if :

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  7. Q.71 mark
    xlog⁡xdydx+y=2log⁡xx \log x \dfrac{dy}{dx} + y = 2 \log x is an example of a :

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  8. Q.81 mark
    If a⃗=2i^−j^+k^\vec{a} = 2\hat{i} - \hat{j} + \hat{k} and b⃗=i^+j^−k^\vec{b} = \hat{i} + \hat{j} - \hat{k}, then a⃗\vec{a} and b⃗\vec{b} are :

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  9. Q.91 mark
    If α\alpha, β\beta and γ\gamma are the angles which a line makes with positive directions of x, y and z axes respectively, then which of the following is not true ?

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  10. Q.101 mark
    The restrictions imposed on decision variables involved in an objective function of a linear programming problem are called :

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  11. Q.111 mark
    Let E and F be two events such that P(E)=0⋅1P(E) = 0{\cdot}1, P(F)=0⋅3P(F) = 0{\cdot}3, P(E∪F)=0⋅4P(E \cup F) = 0{\cdot}4, then P(F ∣ E)P(F\,|\,E) is :

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  12. Q.121 mark
    If A and B are two skew symmetric matrices, then (AB+BA)(AB + BA) is :

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  13. Q.131 mark
    If ∣131k01001∣=±6\begin{vmatrix} 1 & 3 & 1 \\ k & 0 & 1 \\ 0 & 0 & 1 \end{vmatrix} = \pm 6, then the value of k is :

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  14. Q.141 mark
    The derivative of 2x2^x w.r.t. 3x3^x is :

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  15. Q.151 mark
    If ∣a⃗∣=2|\vec{a}| = 2 and −3≤k≤2-3 \le k \le 2, then ∣ka⃗∣∈|k\vec{a}| \in :

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  16. Q.161 mark
    If a line makes an angle of π4\dfrac{\pi}{4} with the positive directions of both x-axis and z-axis, then the angle which it makes with the positive direction of y-axis is :

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  17. Q.171 mark
    Of the following, which group of constraints represents the feasible region given below ?

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  18. Q.181 mark
    If A=[200030005]A = \begin{bmatrix} 2 & 0 & 0 \\ 0 & 3 & 0 \\ 0 & 0 & 5 \end{bmatrix}, then A−1A^{-1} is :

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  19. Questions number 19 and 20 are Assertion and Reason based questions. Two statements are given, one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer from the codes (A), (B), (C) and (D) as given below.
    Q.191 mark
    Assertion (A) : Every scalar matrix is a diagonal matrix. Reason (R) : In a diagonal matrix, all the diagonal elements are 0.

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  20. Q.201 mark
    Assertion (A) : Projection of a⃗\vec{a} on b⃗\vec{b} is same as projection of b⃗\vec{b} on a⃗\vec{a}. Reason (R) : Angle between a⃗\vec{a} and b⃗\vec{b} is same as angle between b⃗\vec{b} and a⃗\vec{a} numerically.

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Section B

2 marks each

  1. Q.212 marks
    Evaluate : sec⁡2(tan⁡−112)+cosec⁡2(cot⁡−113)\sec^2\left(\tan^{-1}\dfrac{1}{2}\right) + \operatorname{cosec}^2\left(\cot^{-1}\dfrac{1}{3}\right)
  2. Q.22 (a)2 marks
    If x=ex/yx = e^{x/y}, prove that dydx=log⁡x−1(log⁡x)2\dfrac{dy}{dx} = \dfrac{\log x - 1}{(\log x)^2}
  3. OR

    Q.22 (b)2 marks
    Check the differentiability of f(x)={x2+1,0≤x<13−x,1≤x≤2f(x) = \begin{cases} x^2 + 1, & 0 \le x < 1 \\ 3 - x, & 1 \le x \le 2 \end{cases} at x=1x = 1.
  4. Q.23 (a)2 marks
    Evaluate : ∫0π/2sin⁡2xcos⁡3x dx\int\limits_{0}^{\pi/2} \sin 2x \cos 3x\, dx
  5. OR

    Q.23 (b)2 marks
    Given ddxF(x)=12x−x2\dfrac{d}{dx} F(x) = \dfrac{1}{\sqrt{2x - x^2}} and F(1)=0F(1) = 0, find F(x)F(x).
  6. Q.242 marks
    Find the position vector of point C which divides the line segment joining points A and B having position vectors i^+2j^−k^\hat{i} + 2\hat{j} - \hat{k} and −i^+j^+k^-\hat{i} + \hat{j} + \hat{k} respectively in the ratio 4 : 1 externally. Further, find ∣AB→∣:∣BC→∣|\overrightarrow{AB}| : |\overrightarrow{BC}|.
  7. Q.252 marks
    Let a⃗\vec{a} and b⃗\vec{b} be two non-zero vectors. Prove that ∣a⃗×b⃗∣≤∣a⃗∣∣b⃗∣|\vec{a} \times \vec{b}| \le |\vec{a}||\vec{b}|. State the condition under which equality holds, i.e., ∣a⃗×b⃗∣=∣a⃗∣∣b⃗∣|\vec{a} \times \vec{b}| = |\vec{a}||\vec{b}|.

Section C

3 marks each

  1. Q.26 (a)3 marks
    If xcos⁡(p+y)+cos⁡psin⁡(p+y)=0x \cos (p + y) + \cos p \sin (p + y) = 0, prove that cos⁡pdydx=−cos⁡2(p+y)\cos p \dfrac{dy}{dx} = -\cos^2 (p + y), where p is a constant.
  2. OR

    Q.26 (b)3 marks
    Find the value of a and b so that function f defined as : f(x)={x−2∣x−2∣+a,if x<2a+b,if x=2x−2∣x−2∣+b,if x>2f(x) = \begin{cases} \dfrac{x - 2}{|x - 2|} + a, & \text{if } x < 2 \\ a + b, & \text{if } x = 2 \\ \dfrac{x - 2}{|x - 2|} + b, & \text{if } x > 2 \end{cases} is a continuous function.
  3. Q.27 (a)3 marks
    Find the intervals in which the function f(x)=log⁡xxf(x) = \dfrac{\log x}{x} is strictly increasing or strictly decreasing.
  4. OR

    Q.27 (b)3 marks
    Find the absolute maximum and absolute minimum values of the function f given by f(x)=x2+2xf(x) = \dfrac{x}{2} + \dfrac{2}{x}, on the interval [1,2][1, 2].
  5. Q.283 marks
    Find : ∫x2+1(x2+2)(x2+4) dx\int \dfrac{x^2 + 1}{(x^2 + 2)(x^2 + 4)}\, dx
  6. Q.29 (a)3 marks
    Find : ∫2+sin⁡2x1+cos⁡2x ex dx\int \dfrac{2 + \sin 2x}{1 + \cos 2x}\, e^x\, dx
  7. OR

    Q.29 (b)3 marks
    Evaluate : ∫0π/41sin⁡x+cos⁡x dx\int\limits_{0}^{\pi/4} \dfrac{1}{\sin x + \cos x}\, dx
  8. Q.303 marks
    Solve the following linear programming problem graphically : Maximise z=4x+3yz = 4x + 3y, subject to the constraints x+y≤800x + y \le 800 2x+y≤10002x + y \le 1000 x≤400x \le 400 x,y≥0x, y \ge 0.
  9. Q.313 marks
    The chances of P, Q and R getting selected as CEO of a company are in the ratio 4 : 1 : 2 respectively. The probabilities for the company to increase its profits from the previous year under the new CEO, P, Q or R are 0⋅30{\cdot}3, 0⋅80{\cdot}8 and 0⋅50{\cdot}5 respectively. If the company increased the profits from the previous year, find the probability that it is due to the appointment of R as CEO.

Section D

5 marks each

  1. Q.325 marks
    A relation R on set A={−4,−3,−2,−1,0,1,2,3,4}A = \{-4, -3, -2, -1, 0, 1, 2, 3, 4\} be defined as R={(x,y):x+yR = \{(x, y) : x + y is an integer divisible by 2}2\}. Show that R is an equivalence relation. Also, write the equivalence class [2][2].
  2. Q.33 (a)5 marks
    It is given that function f(x)=x4−62x2+ax+9f(x) = x^4 - 62x^2 + ax + 9 attains local maximum value at x=1x = 1. Find the value of 'a', hence obtain all other points where the given function f(x)f(x) attains local maximum or local minimum values.
  3. OR

    Q.33 (b)5 marks
    The perimeter of a rectangular metallic sheet is 300 cm. It is rolled along one of its sides to form a cylinder. Find the dimensions of the rectangular sheet so that volume of cylinder so formed is maximum.
  4. Q.345 marks
    Using integration, find the area of the region enclosed between the circle x2+y2=16x^2 + y^2 = 16 and the lines x=−2x = -2 and x=2x = 2.
  5. Q.35 (a)5 marks
    Find the equation of the line passing through the point of intersection of the lines x1=y−12=z−23\dfrac{x}{1} = \dfrac{y - 1}{2} = \dfrac{z - 2}{3} and x−10=y−3=z−72\dfrac{x - 1}{0} = \dfrac{y}{-3} = \dfrac{z - 7}{2} and perpendicular to these given lines.
  6. OR

    Q.35 (b)5 marks
    Two vertices of the parallelogram ABCD are given as A(−1,2,1)A(-1, 2, 1) and B(1,−2,5)B(1, -2, 5). If the equation of the line passing through C and D is x−41=y+7−2=z−82\dfrac{x - 4}{1} = \dfrac{y + 7}{-2} = \dfrac{z - 8}{2}, then find the distance between sides AB and CD. Hence, find the area of parallelogram ABCD.

Section E

  1. Self-study helps students to build confidence in learning. It boosts the self-esteem of the learners. Recent surveys suggested that close to 50% learners were self-taught using internet resources and upskilled themselves. A student may spend 1 hour to 6 hours in a day in upskilling self. The probability distribution of the number of hours spent by a student is given below : P(X=x)={kx2,for x=1,2,32kx,for x=4,5,60,otherwiseP(X = x) = \begin{cases} kx^2, & \text{for } x = 1, 2, 3 \\ 2kx, & \text{for } x = 4, 5, 6 \\ 0, & \text{otherwise} \end{cases} where x denotes the number of hours. Based on the above information, answer the following questions :
    Q.36 (i)1 mark
    Express the probability distribution given above in the form of a probability distribution table.
  2. Q.36 (ii)1 mark
    Find the value of k.
  3. Q.36 (iii) (a)2 marks
    Find the mean number of hours spent by the student.
  4. OR

    Q.36 (iii) (b)2 marks
    Find P(1<X<6)P(1 < X < 6).
  5. A bacteria sample of certain number of bacteria is observed to grow exponentially in a given amount of time. Using exponential growth model, the rate of growth of this sample of bacteria is calculated. The differential equation representing the growth of bacteria is given as : dPdt=kP\dfrac{dP}{dt} = kP, where P is the population of bacteria at any time 't'. Based on the above information, answer the following questions :
    Q.37 (i)2 marks
    Obtain the general solution of the given differential equation and express it as an exponential function of 't'.
  6. Q.37 (ii)2 marks
    If population of bacteria is 1000 at t=0t = 0, and 2000 at t=1t = 1, find the value of k.
  7. A scholarship is a sum of money provided to a student to help him or her pay for education. Some students are granted scholarships based on their academic achievements, while others are rewarded based on their financial needs. Every year a school offers scholarships to girl children and meritorious achievers based on certain criteria. In the session 2022 – 23, the school offered monthly scholarship of ₹ 3,000 each to some girl students and ₹ 4,000 each to meritorious achievers in academics as well as sports. In all, 50 students were given the scholarships and monthly expenditure incurred by the school on scholarships was ₹ 1,80,000. Based on the above information, answer the following questions :
    Q.38 (i)1 mark
    Express the given information algebraically using matrices.
  8. Q.38 (ii)1 mark
    Check whether the system of matrix equations so obtained is consistent or not.
  9. Q.38 (iii) (a)2 marks
    Find the number of scholarships of each kind given by the school, using matrices.
  10. OR

    Q.38 (iii) (b)2 marks
    Had the amount of scholarship given to each girl child and meritorious student been interchanged, what would be the monthly expenditure incurred by the school ?