Bihar School Examination Board (BSEB) Class 8 Mathematics: Mensuration

Instructions. Answer all questions. Fill exactly one bubble per question on the OMR sheet.

1. Mensuration

   1.

   The area of a square field is $144 \text{ m}^2$. What is the length of its side?

   1. (A)

      36 m

   2. (B)

      72 m

   3. (C)

      14 m

   4. (D)

      12 m

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   Answer: (D)

   12 m

   The area of a square is given by side squared. To find the side length, take the square root of the area: $\sqrt{144} = 12$ m.

   Mensuration · Easy

2. 2.

   The perimeter of a rectangular park is $240 \text{ m}$. If its length is $80 \text{ m}$, what is its breadth?

   1. (A)

      60 m

   2. (B)

      40 m

   3. (C)

      160 m

   4. (D)

      80 m

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   Answer: (A)

   60 m

   The perimeter of a rectangle is $2(l+b)$. Given $2(80+b) = 240$, so $80+b = 120$, which means $b = 40$ m.

   Mensuration · Medium

3. 3.

   A cylinder has a radius of $7 \text{ cm}$ and a height of $10 \text{ cm}$. What is its curved surface area? (Use $\pi = 22/7$)

   1. (A)

      $770 \text{ cm}^2$

   2. (B)

      $440 \text{ cm}^2$

   3. (C)

      $154 \text{ cm}^2$

   4. (D)

      $308 \text{ cm}^2$

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   Answer: (B)

   $440 \text{ cm}^2$

   The curved surface area of a cylinder is $2\pi rh$. Substituting the values, $2 \times (22/7) \times 7 \times 10 = 440 \text{ cm}^2$.

   Mensuration · Medium

4. 4.

   The area of a rhombus is $120 \text{ cm}^2$. If one of its diagonals is $10 \text{ cm}$, what is the length of the other diagonal?

   1. (A)

      6 cm

   2. (B)

      24 cm

   3. (C)

      20 cm

   4. (D)

      12 cm

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   Answer: (B)

   24 cm

   The area of a rhombus is $\frac{1}{2} d_1 d_2$. Given $120 = \frac{1}{2} \times 10 \times d_2$, so $120 = 5 d_2$, which means $d_2 = 24 \text{ cm}$.

   Mensuration · Hard

5. 5.

   A cube has a side length of $5 \text{ cm}$. What is its total surface area?

   1. (A)

      $60 \text{ cm}^2$

   2. (B)

      $125 \text{ cm}^2$

   3. (C)

      $150 \text{ cm}^2$

   4. (D)

      $25 \text{ cm}^2$

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   Answer: (C)

   $150 \text{ cm}^2$

   The total surface area of a cube is $6a^2$. Substituting the side length $a=5 \text{ cm}$, the area is $6 \times 5^2 = 6 \times 25 = 150 \text{ cm}^2$.

   Mensuration · Easy

— End of the paper · updated 14 October 2026 —