SOLVED PAPER 2020 (CDS) (II) (Elementary Mathematics)

Total Questions: 100

71. In a triangle, values of all the angles are integers (in degree measure). Which one of the following cannot be the proportion of their measures?

Correct Answer: (d) 6 : 7 : 8
Solution:In triangle, angle of triangle are integers.

72. The length of a rectangle is increased by 10% and breadth is decreased by 10%. Then, the area of the new rectangle is

Correct Answer: (c) decreased by 1%
Solution:Let the length of rectangle = 𝓍 m

73. The surface areas of two spheres are in the ratio 1: 4. What is the ratio of their volumes?

Correct Answer: (d) 1 : 8
Solution:


74. The length, breadth and height of a brick are 20 cm, 15 cm and 10 cm respectively. The number of bricks required to construct a wall with dimensions 45 m length, 0.15 m breadth and 3 m height is

Correct Answer: (c) 6750
Solution:Given, l = 20 cm, b = 15 cm, h = 10 cm

75. If the sum of all interior angles of a regular polygon is twice the sum of all its exterior angles, then the polygon is

Correct Answer: (a) Hexagon
Solution:Interior angle of regular polygon

76. A bicycle wheel makes 5000 revolutions in moving 11 km. What is the radius of the wheel? (Assume π = ²²⁄₇)

Correct Answer: (b) 35 cm
Solution:We have,

77. The volumes of two cones are in the ratio 1 : 4 and their diameters are in the ratio 4 : 5. What is the ratio of their heights?

Correct Answer: (a) 25 : 64
Solution:


78. In a triangle ABC, if 2 ∠A = 3 ∠B = 6 ∠C, then what is ∠A + ∠C equal to ?

Correct Answer: (b) 120°
Solution:

79. If the perimeter of a circle and a square are equal, then what is the ratio of the area of the circle to that of the square ?

Correct Answer: (d) 4 : π
Solution:Given,

80. The lengths of the sides of a right - angled triangle are consecutive even integers (in cm). What is the product of these integers?

Correct Answer: (d) 480
Solution: