Mensuration (Railway Maths) (Part – VII)

Total Questions: 50

11. A cylinder and a cone have the same height and the same radius as that of their base. The ratio of the volume of the cone to the volume of the cylinder is: [RRB NTPC 28/01/2021 (Evening)]

Correct Answer: (b) 1 : 3
Solution:

12. How many cubes of side 3 cm can be formed by melting a cuboid of length 9 cm, breadth 6 cm, and height 6 cm? [RRB NTPC 29/01/2021 (Morning)]

Correct Answer: (b) 12
Solution:

13. In a building, there are 24 cylindrical pillars. The radius of each pillar is 28 cm and height is 4 m. Find the total cost of painting the curved surface area of all the pillars at the rate of Rs 8 per m². [RRB NTPC 29/01/2021 (Morning)]

Correct Answer: (d) Rs. 1,351.68
Solution:

14. 3 cubes each with a side 16 cm are joined side by side in a line. Find the surface area of the cuboid so formed. [RRB NTPC 30/01/2021 (Morning)]

Correct Answer: (c) 3584 cm²
Solution:

When we join 3 cubes, then
l = 48 cm, b = 16 cm and h = 16 cm
Area of cuboid formed = 2(16×16 + 16 × 48 + 16 × 48)
= 3584 cm²

15. If the height and the radius of a solid right circular cylinder are doubled, find the percentage increase in its volume. [RRB NTPC 30/01/2021 (Morning)]

Correct Answer: (a) 700%
Solution:

16. The internal measures of a cuboidal room are 12 m, 8 m, 4 m with the height being 4 m. Find the total cost of whitewashing all four walls along with the ceiling of the room, if the cost of white washing is Rs 5 per sq m ? [RRB NTPC 30/01/2021 (Evening)]

Correct Answer: (d) Rs 1280
Solution:

17. If the volume of a sphere is given as 4851 cm³, then find its diameter. (Use π = 22/7) [RRB NTPC 31/01/2021 (Morning)]

Correct Answer: (d) 21 cm
Solution:

18. An aquarium is in the form of a cuboid whose external measures are 80 cm × 30 cm × 40 cm. The base, side faces and back face are to be covered with a coloured paper. Find the area of the paper needed? [RRB NTPC 31/01/2021 (Evening) ]

Correct Answer: (b) 8000 cm²
Solution:

19. Find the number of bricks measuring 25 cm in length, 5 cm in breadth and 20 cm in height for a wall 40 m long, 80 cm broad and 6 m in height. [RRB NTPC 31/01/2021 (Evening)]

Correct Answer: (c) 76800
Solution:

20. What is the ratio of volumes of two spheres where the curved surface areas are in the ratio of 1 : 4? [RRB NTPC 01/02/2021 (Evening)]

Correct Answer: (c) 1 : 8
Solution: