SOLVED PAPER 2021 (CDS) (II) (Elementary Mathematics)

Total Questions: 100

1. The radius of circum-circle of a right angled triangle is 10 cm and the altitude drawn to the hypotenuse is 8 cm. What is the area of the triangle?

Correct Answer: (b) 80 cm²
Solution:


2. Two circles touch externally. The sum of their areas is 41pi square cm. If the distance between their centres is 9 cm, then what is difference between their diameters

Correct Answer: (c) 2 cm
Solution:


3. Solve it ?

Correct Answer: (d)
Solution:


4. The area of a rhombus is 336 sq cm. If the length of one of its diagonals is 48 cm, then what is the perimeter of the rhombus?

Correct Answer: (c) 100 cm
Solution:


5. The minute hand of a clock is 21 cm long. What is the area on the face of the clock described by the minute hand between 10:10 am and 10:30 am? (Take π = ²²⁄₇)

Correct Answer: (c) 462 cm²
Solution:


6. The length and breadth of a room are 21 m and 16 m respectively. If the length of the longest rod that can be placed in the room is 29 m, then what is the height of the room?

Correct Answer: (c) 12 m
Solution:

7. A hemispherical bowl of internal radius 18 cm contains a liquid. The liquid is filled in small cylindrical bottles of internal radius 3 cm and internal height 4 cm. What is the number of bottles used to empty the bowl?

Correct Answer: (c) 108
Solution:


8. A hollow spherical shell is made of a metal of density 7g/cm³ If its internal and external radii are 3 cm and 6 cm respectively, then what is the mass of the shell ? (Take π = ²²⁄₇)

Correct Answer: (d) 5544 g
Solution:

9. A cone of height 16 cm and diameter 14 cm is mounted on a hemisphere of same diameter. What is the volume of the solid thus formed? (Take π = ²²⁄₇)

Correct Answer: (a) 1540 cm³
Solution:

10. 3 cubes each of volume 343 cm³ are joined end to end. What is the total surface area of the resulting cuboid?

Correct Answer: (c) 686 cm²
Solution: