Mensuration (Railway Maths) (Part – VI)

Total Questions: 50

41. The diameters of the bases of the two cones are equal. If their slant heights are in the ratio of 3 : 4, then what will the ratio of their curved surface areas be? [RRB NTPC 22/01/2021 (Morning) ]

Correct Answer: (d) 3 : 4
Solution:

Ratio of both cone curved surface areas = πr × 3 : πr × 4 = 3 : 4

42. The diameter of a hemisphere is 7 cm. What will be its total surface area? [RRB NTPC 22/01/2021 (Morning) ]

Correct Answer: (d) 115.50 cm²
Solution:

43. If a map of a city was drawn on a scale of 0.05 centimetres to a kilometre, what area would represent a country if it has an area of 8000 square kilometres? [RRB NTPC 22/01/2021 (Morning)]

Correct Answer: (c) 20 cm²
Solution:

As area of 1 km² = 0.0025 cm²
So 8000 km² = 0.0025 × 8000 = 20 cm²

44. Area of a square is equal to ten times the area of a rectangle of edge 5 cm × 8 cm. What is the Perimeter of the square? [RRB NTPC 22/01/2021 (Evening)]

Correct Answer: (b) 80 cm
Solution:

Area of square = 10 × area of rectangle
a² = 10 × 5 × 8 = a = 20
Perimeter of the square
=4 × a = 4 × 20 = 80 cm

45. Which of the four options provided below will be the closest to the area of an equilateral triangle, each of whose sides is 10 m long? [RRB NTPC 23/01/2021 (Morning)]

Correct Answer: (c) 43.25 m²
Solution:

46. There are 3 pieces of wooden logs which are 48 m, 56 m and 72 m long. What is the greatest possible length by which these can be completely measured? [RRB NTPC 23/01/2021 (Morning)]

Correct Answer: (d) 8 m
Solution:

HCF of (48, 56, 72) = 8 m

47. The area of a square is 36 cm². Find the area of the square formed by joining the mid-points of its sides. [RRB NTPC 25/01/2021 (Morning)]

Correct Answer: (a) 18 cm²
Solution:

48. 784 square tiles, each of side 50 cm are required to tile a floor of a square room. Find the length of the sides of the room. [RRB NTPC 25/01/2021 (Morning)]

Correct Answer: (d) 14 m
Solution:

49. The cost of fencing a rectangular field at Rs. 24 per meter is Rs. 1,920. If its length is 23 m, find its breadth. [RRB NTPC 25/01/2021 (Morning)]

Correct Answer: (a) 17 m
Solution:

50. The ratio of the length to the breadth of a rectangular field is 6 : 5. If the breadth is 25 m less than the length. The perimeter of the field is ? [RRB NTPC 25/01/2021 (Evening)]

Correct Answer: (b) 550 m
Solution: