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Question

From a rectangular cardboard sheet of length 46 m and breadth 8 m, three circular plates of radii 3 m, 2 m and 1 m are cut out. If the area of the remaining part of the cardboard sheet is equal to the area of a square, then find the length of each side of the square (use π = 22/7).

This question was previously asked in
RRB NTPC 2024 Undergraduate CBT 1 Question Paper (29-Aug-2025) (Shift 1)
The correct answer is

18 m

Here's how to solve this problem step-by-step:

1. Calculate the area of the rectangular cardboard sheet:

Area of rectangle = length × breadth = 46 m × 8 m = 368 \(m^2\)

2. Calculate the area of each circular plate:

  • Area of circle 1 (radius 3 m) = π × \(3^2\) = \( \frac{22}{7} \times 9 = \frac{198}{7} m^2\)
  • Area of circle 2 (radius 2 m) = π × \(2^2\) = \( \frac{22}{7} \times 4 = \frac{88}{7} m^2\)
  • Area of circle 3 (radius 1 m) = π × \(1^2\) = \( \frac{22}{7} \times 1 = \frac{22}{7} m^2\)

3. Calculate the total area of the three circular plates:

Total area = \(\frac{198}{7} + \frac{88}{7} + \frac{22}{7} = \frac{308}{7} = 44 m^2\)

4. Calculate the area of the remaining part of the cardboard sheet:

Remaining area = Area of rectangle - Total area of circles = 368 \(m^2\) - 44 \(m^2\) = 324 \(m^2\)

5. Find the side length of the square with the same area as the remaining part of the cardboard:

Area of square = side × side = \(side^2\) = 324 \(m^2\)

Side = \(\sqrt{324}\) = 18 m

Therefore, the length of each side of the square is 18 m.

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Similar Questions

  1. The volume of a wall that is 5 times as high as it is broad and 8 times as long as it is high is 12.8 cubic meters. Find the breadth of the wall.
  2. If the radius of a sphere is increased by 2 cm, then its surface area increases by 704 cm\(^2\). Using \(\pi = \frac{22}{7}\), find the radius of the sphere after the increase.
  3. The volume of a solid cylinder is 5,236 cm$^3$ and its height is 34 cm. What is the total surface area of the solid cylinder? $\left(\text{Use } \pi = \frac{22}{7}\right)$
  4. Find the area of a regular hexagon whose side measures \(18\sqrt{2}\) cm. (Use \(\sqrt{3} = 1.73\))
  5. The sides of the rectangle are in the ratio 8 : 10 and its perimeter is 90 cm. The area of this rectangle is:

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  7. If the sum of lengths of two adjacent sides of a parallelogram is 12 cm, then the perimeter of the parallelogram is:

  8. In a workshop calculation, you need to find the side of a square base with an area of 64 cm2. What is the correct length?

  9. Calculate the area of an irregular plot using the Trapezoidal Rule, given the offsets are 2 m, 4 m, 3 m, and 5 m at an equal spacing of 1 m.

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Important Questions from Mensuration

  1. The volume of a wall that is 5 times as high as it is broad and 8 times as long as it is high is 12.8 cubic meters. Find the breadth of the wall.
  2. If the radius of a sphere is increased by 2 cm, then its surface area increases by 704 cm\(^2\). Using \(\pi = \frac{22}{7}\), find the radius of the sphere after the increase.
  3. What is the perimeter of an equilateral triangle with side 13 cm?
  4. The perimeter of a square is 76 m. Its area (in $m^2$) is:
  5. A cylindrical rod has an outer curved surface area of 1800 cm$^2$. If the length of the rod is 52 cm, then the outer radius (in cm) of the rod, correct to two places of decimal, is:
    Take $\pi = \frac{22}{7}$
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