Mensuration (Railway Maths) (Part – I)

Total Questions: 50

21. A rectangle with dimension of 24 cm and 28 cm was reconstructed to make a rhombus with the same perimeter as that of the rectangle and 120°as one of its angles. The area of the rhombus was: [NTPC CBT - I 02/03/2021 (Morning) ]

Correct Answer: (d)
Solution:

22. When the radius of a wheel is increased by 8% then find the ratio of the number of revolutions required by the old to the new wheel in traveling a distance of 100 m. [NTPC CBT - I 02/03/2021 (Evening) ]

Correct Answer: (a) 27 : 25
Solution:

23. If the length of a rectangle is doubled, what change should be made in its breadth so that its area remains the same? [NTPC CBT - I 03/03/2021 (Evening) ]

Correct Answer: (a) Breadth should be halved
Solution:

24. A pyramid is placed on a cube of side 10 cm such that the base of the pyramid is completely aligned with the top face of the cube. The altitude of the pyramid is thrice the side of the cube. Find the volume of the entire object. [NTPC CBT - I 11/03/2021 (Evening) ]

Correct Answer: (a) 2000 cm³
Solution:

25. A cylindrical vessel of inner radius 4 cm contains water up to some height. A solid sphere of radius 3 cm is lowered into the water until it is completely immersed. The water level in the vessel will rise by. [NTPC CBT - I 12/03/2021 (Evening)]

Correct Answer: (c) 9/4 cm
Solution:

26. From a circular sheet of radius 20 cm, three circles of radius 6 cm each are cut off. What is the ratio of the area of uncut to the area of the cut portion? [NTPC CBT - I 19/03/2021 (Evening)]

Correct Answer: (d) 73:27
Solution:

27. In a cuboid, the sum of the squares of its three dimensions is equal to half of its total surface area. If the volume of the cuboid is 729 cm³, then find its lateral surface area (in cm²). [NTPC CBT - I 31/07/2021 (Morning)]

Correct Answer: (d) 324
Solution:

28. A 2 m broad pathway is to be constructed around a rectangular plot on the inside. The area of the plot is 96 m². The rate of construction is Rs.50 per m². Find the total cost of the construction. [RRB JE 25/05/2019 (Morning)]

Correct Answer: (b) Data insufficient
Solution:

29. A room is 15 ft long and 12 ft broad. A mat has to be placed on the floor of this room leaving 1.5 ft space from the walls. What will be the cost of the mat at the rate of Rs.3.50 per square foot? [RRB JE 30/05/2019 (Afternoon)]

Correct Answer: (b) Rs. 378
Solution:

30. A hemispherical portion is scooped out of a wooden block such that the diameter "I' of the hemisphere equals the edge of the cubical block. What is the surface area of the resulting solid ? [RRB JE 26/06/2019 (Morning) ]

Correct Answer: (a)
Solution: