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CDS (I) 2020, Elementary Mathematics question paper

100 questions · 100 marks · 120 minutes · +1 per correct answer, -0.33 per wrong one

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  1. 1
    The number 2×3×5×7×11+12 \times 3 \times 5 \times 7 \times 11 + 1 is

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  2. 2
    Two unequal pairs of numbers satisfy the following conditions : (i) The product of the two numbers in each pair is 2160 (ii) The HCF of the two numbers in each pair is 12. If xx is the mean of the numbers in the first pair and yy is the mean of the numbers in the second pair, then what is the mean of xx and yy ?

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  3. 3
    How many digits are there in (54)10(54)^{10} ? (Given that log⁡102=0.301\log_{10} 2 = 0.301 and log⁡103=0.477\log_{10} 3 = 0.477)

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  4. 4
    Which one of the following is a set of solutions of the equation xx=xxnx^{\sqrt{x}} = \sqrt[n]{x^{x}}, if nn is a positive integer ?

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  5. 5
    In a competitive examination, 250 students have registered. Out of these, 50 students have registered for Physics, 75 students for Mathematics and 35 students for both Mathematics and Physics. What is the number of students who have registered neither for Physics nor for Mathematics ?

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  6. 6
    If the sum of the digits of a number 10n−110^{n} - 1, where nn is a natural number, is equal to 3798, then what is the value of nn ?

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  7. 7
    Which one of the following is the largest number among 222222222^{2}, 22222222^{22}, 2222222^{222}, 222222^{2222} ?

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  8. 8
    If mm is the number of prime numbers between 0 and 50; and nn is the number of prime numbers between 50 and 100, then what is (m−n)(m - n) equal to ?

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  9. 9
    If ab=13\frac{a}{b} = \frac{1}{3}, bc=2\frac{b}{c} = 2, cd=12\frac{c}{d} = \frac{1}{2}, de=3\frac{d}{e} = 3 and ef=14\frac{e}{f} = \frac{1}{4}, then what is the value of abcdef\frac{abc}{def} ?

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  10. 10
    Which one of the following is the largest divisor of 3x+3x+1+3x+23^{x} + 3^{x+1} + 3^{x+2}, if xx is any natural number ?

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  11. 11
    A two-digit number is 9 more than four times of the number obtained by interchanging its digits. If the product of digits in the two-digit number is 8, then what is the number ?

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  12. 12
    If α\alpha and β\beta are the roots of the quadratic equation x2+kx−15=0x^{2} + kx - 15 = 0 such that α−β=8\alpha - \beta = 8, then what is the positive value of kk ?

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  13. 13
    What are the values of pp and qq respectively, if (x−1)(x - 1) and (x+2)(x + 2) divide the polynomial x3+4x2+px+qx^{3} + 4x^{2} + px + q ?

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  14. 14
    If (x+k)(x + k) is the HCF of x2+5x+6x^{2} + 5x + 6 and x2+8x+15x^{2} + 8x + 15, then what is the value of kk ?

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  15. 15
    If 5x+1−5x−1=6005^{x+1} - 5^{x-1} = 600, then what is the value of 102x10^{2x} ?

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  16. 16
    A number divides 12288, 28200 and 44333 so as to leave the same remainder in each case. What is that number ?

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  17. 17
    If x2+9y2=6xyx^{2} + 9y^{2} = 6xy, then what is y:xy : x equal to ?

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  18. 18
    If mm and nn are positive integers such that mn=1331m^{n} = 1331, then what is the value of (m−1)n−1(m - 1)^{n-1} ?

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  19. 19
    What is 1am−n−1+1an−m−1\frac{1}{a^{m-n} - 1} + \frac{1}{a^{n-m} - 1} equal to ?

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  20. 20
    If x=2x = \sqrt{2}, y=33y = \sqrt[3]{3} and z=66z = \sqrt[6]{6}, then which one of the following is correct ?

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  21. 21
    If log⁡x=1.2500\log x = 1.2500 and y=xlog⁡xy = x^{\log x}, then what is log⁡y\log y equal to ?

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  22. 22
    If f(x)f(x) is divided by (x−α)(x−β)(x - \alpha)(x - \beta) where α≠β\alpha \ne \beta, then what is the remainder ?

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  23. 23
    If the area of a square is 2401x4+196x2+42401x^4 + 196x^2 + 4, then what is its side length ?

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  24. 24
    If xx varies as yzyz, then yy varies inversely as

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  25. 25
    If the points PP and QQ represent real numbers 0.73‾0.7\overline{3} and 0.56‾0.5\overline{6} on the number line, then what is the distance between PP and QQ ?

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  26. 26
    What is the point on the xyxy-plane satisfying 5x+2y=7xy5x + 2y = 7xy and 10x+3y=8xy10x + 3y = 8xy ?

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  27. 27
    The price of an article XX increases by 20% every year and price of article YY increases by 10% every year. In the year 2010, the price of article XX was Rs. 5000 and price of article YY was Rs. 2000. In which year the difference in their prices exceeded Rs. 5000 for the first time ?

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  28. 28
    The ratio of speeds of XX and YY is 5:65 : 6. If YY allows XX a start of 70 m in a 1.2 km race, then who will win the race and by what distance ?

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  29. 29
    A train takes two hours less for a journey of 300 km if its speed is increased by 5 km/hr from its usual speed. What is its usual speed ?

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  30. 30
    If 6 men and 8 women can do a piece of work in 10 days; and 13 men and 24 women can do the same work in 4 days, then what is the ratio of daily work done by a man to that of a woman ?

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  31. 31
    Students of a class are made to sit in rows of equal number of chairs. If number of students is increased by 2 in each row, then the number of rows decreases by 3. If number of students is increased by 4 in each row, then the number of rows decreases by 5. What is the number of students in the class ?

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  32. 32
    A sum was put at simple interest at certain rate for 2 years. Had it been put at 1% higher rate of interest, it would have fetched Rs. 24 more. What is the sum ?

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  33. 33
    The population of two villages is 1525 and 2600 respectively. If the ratio of male to female population in the first village is 27:3427 : 34 and the ratio of male to female population in the second village is 6:76 : 7, then what is the ratio of male to female population of these two villages taken together ?

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  34. 34
    In a class room the ratio of number of girls to that of boys is 3:43 : 4. The average height of students in the class is 4.6 feet. If the average height of the boys in the class is 4.8 feet, then what is the average height of the girls in the class ?

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  35. 35
    What is the median of the data 3, 5, 9, 4, 6, 11, 18 ?

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  36. 36
    In a pi-diagram there are three sectors. If the ratio of the angles of the sectors is 1:2:31 : 2 : 3, then what is the angle of the largest sector ?

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  37. 37
    The maximum marks in a Test are converted from 250 to 50 for the purpose of an Internal Assessment. The highest marks scored were 170 and lowest marks were 70. What is the difference between the maximum and minimum marks scored in the Internal Assessment ?

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  38. Directions for the following three (03) items : Read the following information and answer the three items that follow : The following data presents count of released convicts who have served prison terms XX, those who have received some educational or technical training during their term YY and those who were offered Company placement ZZ respectively, from six different jails A, B, C, D, E and F, in the year 2010.
    XXYYZZ
    A864525
    B1305903461
    C2019940474
    D1166869416
    E954544254
    F1198464174
    38
    Jails with highest and smallest percentage of trained convicts are respectively

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  39. 39
    Jail with highest placement rate of trained convicts is

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  40. 40
    Jails from which more than half of the trained convicts are offered jobs, are

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  41. 41
    The number of three digit numbers (all digits are different) which are divisible by 7 and also divisible by 7 on reversing the order of the digits, is

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  42. 42
    How many integral values of xx and yy satisfy the equation 5x+9y=75x + 9y = 7, where −500<x<500-500 < x < 500 and −500<y<500-500 < y < 500?

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  43. 43
    Let XYZXYZ be a 3-digit number. Let S=XYZ+YZX+ZXYS = XYZ + YZX + ZXY. Which of the following statements is/are correct? 1. SS is always divisible by 3 and (X+Y+Z)(X + Y + Z) 2. SS is always divisible by 9 3. SS is always divisible by 37 Select the correct answer using the code given below:

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  44. 44
    In covering certain distance, the average speeds of XX and YY are in the ratio 4:54 : 5. If XX takes 45 minutes more than YY to reach the destination, then what is the time taken by YY to reach the destination?

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  45. 45
    For two observations, the sum is SS and product is PP. What is the harmonic mean of these two observations?

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  46. 46
    If the annual income of XX is 20% more than that of YY, then the income of YY is less than that of XX by pp%. What is the value of pp?

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  47. 47
    What is the least perfect square which is divisible by 3, 4, 5, 6 and 7?

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  48. 48
    In a water tank there are two outlets. It takes 20 minutes to empty the tank if both the outlets are opened. If the first outlet is opened, the tank is emptied in 30 minutes. What is the time taken to empty the tank by second outlet?

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  49. 49
    If (x2−1)(x^2 - 1) is a factor of ax4+bx3+cx2+dx+eax^4 + bx^3 + cx^2 + dx + e, then which one of the following is correct?

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  50. 50
    If (x8+1x8)=47\left(x^8 + \frac{1}{x^8}\right) = 47, what is the value of (x6+1x6)\left(x^6 + \frac{1}{x^6}\right)?

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  51. 51
    A wheel makes 360 revolutions in one minute. What is the number of radians it turns in one second?

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  52. 52
    What is the least value of (25 cosec⁡2x+sec⁡2x)(25\,\operatorname{cosec}^2 x + \sec^2 x)?

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  53. 53
    Let 0<θ<90∘0 < \theta < 90^\circ and 100θ=90∘100\theta = 90^\circ. If α=∏n=199cot⁡nθ\alpha = \prod_{n=1}^{99} \cot n\theta, then which one of the following is correct?

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  54. 54
    If tan⁡6θ=cot⁡2θ\tan 6\theta = \cot 2\theta, where 0<6θ<π20 < 6\theta < \frac{\pi}{2}, then what is the value of sec⁡4θ\sec 4\theta?

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  55. 55
    A tree of height 15 m is broken by wind in such a way that its top touches the ground and makes an angle 30∘30^\circ with the ground. What is the height from the ground to the point where tree is broken?

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  56. 56
    On a plane area there are two vertical towers separated by 100 feet apart. The shorter tower is 40 feet tall. A pole of length 6 feet stands on the line joining the base of two towers so that the tip of the towers and tip of the pole are also on the same line. If the distance of the pole from the shorter tower is 75 feet, then what is the height of the taller tower (approximately)?

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  57. 57
    The angles of elevation of the top of a tower from two points at distances pp and qq from the base and on the same straight line are 27∘27^\circ and 63∘63^\circ respectively. What is the height of the tower?

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  58. 58
    What is the value of sin⁡26∘+sin⁡212∘+sin⁡218∘+…+sin⁡284∘+sin⁡290∘\sin^2 6^\circ + \sin^2 12^\circ + \sin^2 18^\circ + \ldots + \sin^2 84^\circ + \sin^2 90^\circ?

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  59. 59
    What is cos⁡θ1+sin⁡θ+1cot⁡θ\frac{\cos\theta}{1 + \sin\theta} + \frac{1}{\cot\theta} equal to?

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  60. 60
    What is sin⁡θ−cos⁡θ+1sin⁡θ+cos⁡θ−1−sin⁡θ+1cos⁡θ\frac{\sin\theta - \cos\theta + 1}{\sin\theta + \cos\theta - 1} - \frac{\sin\theta + 1}{\cos\theta} equal to ?

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  61. 61
    What is (tan⁡x+tan⁡y)(1−cot⁡xcot⁡y)+(cot⁡x+cot⁡y)(1−tan⁡xtan⁡y)(\tan x + \tan y)(1 - \cot x \cot y) + (\cot x + \cot y)(1 - \tan x \tan y) equal to ?

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  62. 62
    What is sec⁡x−tan⁡xsec⁡x+tan⁡x\sqrt{\frac{\sec x - \tan x}{\sec x + \tan x}} equal to ?

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  63. 63
    If θ\theta lies in the first quadrant and cot⁡θ=6316\cot\theta = \frac{63}{16}, then what is the value of (sin⁡θ+cos⁡θ)(\sin\theta + \cos\theta) ?

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  64. 64
    What is the value of 1−2sin⁡2θcos⁡2θsin⁡4θ+cos⁡4θ+4\frac{1 - 2\sin^2\theta\cos^2\theta}{\sin^4\theta + \cos^4\theta} + 4 equal to ?

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  65. 65
    A rectangle is 48 cm long and 14 cm wide. If the diagonal makes an angle θ\theta with the longer side, then what is (sec⁡θ+cosec⁡θ)(\sec\theta + \operatorname{cosec}\theta) equal to ?

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  66. 66
    What is the area of the triangle having side lengths yz+zx\frac{y}{z} + \frac{z}{x}, zx+xy\frac{z}{x} + \frac{x}{y}, xy+yz\frac{x}{y} + \frac{y}{z} ?

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  67. 67
    If the angles of a triangle are 30∘30^\circ and 45∘45^\circ and the included side is (3+1)(\sqrt{3} + 1) cm, then what is the area of the triangle ?

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  68. 68
    ABCDABCD is a plate in the shape of a parallelogram. EFEF is the line parallel to DADA and passing through the point of intersection OO of the diagonals ACAC and BDBD. Further, EE lies on DCDC and FF lies on ABAB. The triangular portion DOEDOE is cut out from the plate ABCDABCD. What is the ratio of area of remaining portion of the plate to the whole ?

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  69. 69
    Two circles of radii 20 cm and 16 cm intersect and the length of common chord is 24 cm. If dd is the distance between their centres, then which one of the following is correct ?

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  70. 70
    In a circle of radius 5 cm, ABAB and ACAC are two chords such that AB=AC=8AB = AC = 8 cm. What is the length of chord BCBC ?

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  71. 71
    Two circles touch internally. The sum of their areas is 136π136\pi cm2^2 and distance between their centres is 4 cm. What are the radii of the circles ?

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  72. 72
    If area of a circle and a square are same, then what is the ratio of their perimeters ?

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  73. 73
    A circle of diameter 8 cm is placed in such a manner that it touches two perpendicular lines. Then another smaller circle is placed in the gap such that it touches the lines and the circle. What is the diameter of the smaller circle ?

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  74. 74
    The thickness of a cylinder is 1 foot, the inner radius of the cylinder is 3 feet and height is 7 feet. To paint the inner surface it requires one litre of a particular colour. How much quantity of the same colour is required to paint all the surfaces of the cylinder ?

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  75. 75
    A square and a rectangle have equal areas. If one side of the rectangle is of length numerically equal to the square of the length of the side of the square then the other side of the rectangle is

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  76. 76
    The length and breadth of a rectangle are in the ratio 4:34 : 3. Then what is the ratio of the area of the triangle formed by the parts of the diagonals with a long side to the area of the triangle formed by the parts of diagonals with a short side ?

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  77. 77
    Suppose a region is formed by removing a sector of 20∘20^\circ from a circular region of radius 30 feet. What is the area of this new region ?

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  78. 78
    ABCDABCD is a parallelogram where ACAC and BDBD are the diagonals. If ∠BAD=60∘\angle BAD = 60^\circ, ∠ADB=90∘\angle ADB = 90^\circ, then what is BD2BD^2 equal to ?

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  79. 79
    A line through the vertex AA of a parallelogram ABCDABCD meets DCDC in PP and BCBC produced in QQ. If PP is the mid-point of DCDC, then which of the following is/are correct ? 1. Area of △PDA\triangle PDA is equal to that of △PCQ\triangle PCQ 2. Area of △QAB\triangle QAB is equal to twice that of △PCQ\triangle PCQ Select the correct answer using the code given below :

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  80. 80
    How many cubic metre of earth is to be dug out to dig a well of radius 1.41.4 m and depth 5 m ?

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  81. 81
    If the diagonals of a rhombus are xx and yy, then what is its area ?

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  82. 82
    The lengths of sides of a triangle are 3x,4y,5z33x, 4\sqrt{y}, 5\sqrt[3]{z}, where 3x<4y<5z33x < 4\sqrt{y} < 5\sqrt[3]{z}. If one of the angles is 90∘90^\circ, then what are the minimum integral values of x,y,zx, y, z respectively ?

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  83. 83
    What is the maximum number of circum-circles that a triangle can have ?

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  84. 84
    If an arc of a circle of radius 6 cm subtends a central angle measuring 30∘30^\circ, then which one of the following is an approximate length of the arc ?

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  85. 85
    A ladder 5 m long is placed in a room so as to reach a point 4.84.8 m high on a wall and on turning the ladder over to the opposite side of the wall without moving the base, it reaches a point 1.41.4 m high. What is the breadth of the room ?

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  86. 86
    What is the area of the largest square plate cut from a circular disk of radius one unit ?

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  87. 87
    Out of 4 identical balls of radius rr, 3 balls are placed on a plane such that each ball touches the other two balls. The 4th4^{\text{th}} ball is placed on them such that this ball touches all the three balls. What is the distance of centre of 4th4^{\text{th}} ball from the plane ?

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  88. 88
    A right circular cylinder just encloses a sphere. If pp is the surface area of the sphere and qq is the curved surface area of the cylinder, then which one of the following is correct ?

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  89. 89
    ABCDABCD is a quadrilateral such that AD=DC=CA=20AD = DC = CA = 20 units, BC=12BC = 12 units and ∠ABC=90∘\angle ABC = 90^\circ. What is the approximate area of the quadrilateral ABCDABCD ?

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  90. 90
    Let PQRSPQRS be the diameter of a circle of radius 9 cm. The length PQPQ, QRQR and RSRS are equal. Semi-circle is drawn with QSQS as diameter (as shown in the given figure). What is the ratio of the shaded region to that of the unshaded region ?

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  91. 91
    What is the area of the shaded region in the given figure, if the radius of each of the circles is 2 cm ?

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  92. 92
    In the given figure, what is the area of the shaded region ?

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  93. 93
    In the given figure, if yx=6\frac{y}{x} = 6 and zx=5\frac{z}{x} = 5, then what is the value of xx ?

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  94. 94
    ABCDABCD is a trapezium, where ABAB is parallel to DCDC. If AB=4AB = 4 cm, BC=3BC = 3 cm, CD=7CD = 7 cm and DA=2DA = 2 cm, then what is the area of the trapezium ?

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  95. 95
    Angles are shown in the given figure. What is value of ∠1+∠2+∠3+∠4+∠5+∠6+∠7+∠8\angle 1 + \angle 2 + \angle 3 + \angle 4 + \angle 5 + \angle 6 + \angle 7 + \angle 8?

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  96. 96
    In the given figure PQPQ is parallel to RSRS, ∠AEF=95∘\angle AEF = 95^\circ, ∠BHS=110∘\angle BHS = 110^\circ, and ∠ABC=x∘\angle ABC = x^\circ. Then what is the value of xx?

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  97. 97
    In the given figure ABAB is parallel to CDCD and ACAC is parallel to BDBD. If ∠EAC=40∘\angle EAC = 40^\circ, ∠FDG=55∘\angle FDG = 55^\circ, ∠HAB=x∘\angle HAB = x^\circ, then what is the value of xx?

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  98. 98
    In the given figure, there are three semi circles ABCABC, AEFAEF and CDFCDF. The distance between AA and CC is 28 units and FF is the mid-point of ACAC. What is the total area of the three semi circles?

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  99. 99
    What is the approximate area of the shaded region in the figure given?

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  100. 100
    Consider the following statements with reference to the given figure: 1. The sum of the areas of △AOD\triangle AOD and △BOC\triangle BOC is equal to the sum of the areas of △AOB\triangle AOB and △DOC\triangle DOC. 2. ∠AOD=∠BOC\angle AOD = \angle BOC 3. AB+BC+CD+DA>AC+BDAB + BC + CD + DA > AC + BD Which of the above statements are correct?

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