Mensuration (Railway Maths) (Part – VIII)

Total Questions: 50

21. If length of each side of a cube is doubled, then the volume ______ the original volume. [RRB NTPC 05/03/2021 (Morning)]

Correct Answer: (c) becomes 8 times
Solution:

Let , length of each side = a
A/Q , length of each side = 2a
Volume of the cube = a³ = (2a)³ = 8 a³
So, we can say that the final volume is 8 times the original volume.

22. Kishore plans to tile his kitchen floor with square tiles. Each side of the tile is 10 cm. The kitchen is 2.4 m long and 1.6 m wide. How many tiles will Kishore need ? [RRB NTPC 07/03/2021 (Morning)]

Correct Answer: (c) 384
Solution:

23. The radius and height of a cylinder are 28 cm and 40 cm, respectively. Find its volume. [RRB NTPC 08/03/2021 (Morning)]

Correct Answer: (d) 98560 cm³
Solution:

The radius and height of a cylinder are 28 cm and 40 cm, respectively.
Then the volume is = 22/7 × 28 × 28 × 40 = 98560 cm³

24. The surface area of a sphere whose radius is 21 m is: [RRB NTPC 08/03/2021 (Morning)]

Correct Answer: (d) 5544 m²
Solution:

Surface area of a sphere = 4ΠR²
= 4 × 22/7 × 21 × 21 ⇒ 5544 m²

25. If the ratio of the areas of two squares is 169 : 196 , then the ratio of their perimeters is : [RRB NTPC 08/03/2021 (Evening) ]

Correct Answer: (d) 13 : 14
Solution:

26. The area of a square is equal to the area of a rectangle. The ratio of the length and the width of the rectangle is 4 : 1. If each edge of the square is 8 cm, what is the perimeter of the rectangle? [RRB NTPC 09/03/2021 (Morning) ]

Correct Answer: (b) 40 cm
Solution:

27. In a right circular cylinder, the ratio of curved surface area to total surface area is 3 : 7. Find the ratio of height to radius of the cylinder. [RRB NTPC 09/03/2021 (Evening)]

Correct Answer: (d) 3 : 4
Solution:

28. If a cube having a side of 8 cm is divided into smaller cubes each having a side of 2 cm, then what will be the total number of smaller cubes each having a side of 2 cm? [RRB NTPC 09/03/2021 (Evening)]

Correct Answer: (c) 64
Solution:

29. The largest sphere is cut off from a solid cube of side 6 cm. The volume of the sphere will be: [RRB NTPC 11/03/2021 (Morning)]

Correct Answer: (c) 36π cm³
Solution:

The diameter of the sphere = side of the solid cube = 6 cm
Radius of the sphere = 3 cm
Volume of the sphere = 4/3π R³
=4/3 × π × 3 × 3 × 3 = 36 π cm³

30. A solid frustum of a cone is of height 8 cm. If the radii of its lower and upper ends are 3 cm and 9 cm respectively, then its slant height is: [RRB NTPC 11/03/2021 (Morning)]

Correct Answer: (c) 10 cm
Solution: