CG Board Class 8 Mathematics Chapter 15 Solutions: Mensuration-II (क्षेत्रमिति-2) – 2026-27

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CG SCERT (Chhattisgarh Board) Class 8 Mathematics Solutions | 2026-27 Official Edition

Complete 100% textbook-grounded CG Board Class 8 Mathematics Chapter 15 Solutions: Mensuration-II (क्षेत्रमिति-2) in Bilingual Format (English & Hindi Medium).

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  • Volume of a Cuboid / :

V = l × b × h = Length × Breadth × Height

  • Volume of a Cube / :

V = S3 = (Side)3

Total Surface Area = 2(lb + bh + hl)

Total Surface Area = 6S2

1 m3 = 1,000,000 cm3 = 106 cm3

1 m3 = 1,000 Litres

SECTION / EXERCISE

EXERCISE 15.1 / 15.1

Question 1

Fill in the blanks


📝 Question:

Fill in the blanks /

💡 Solution:

(i) A cuboid has a total of ___________ faces / ___________ :**

A cuboid has 6 faces.

(ii) Length of a cuboid = (Volume of the cuboid)/(Breadth × )

Blank = Height.

(iii) 1 cubic m = cubic cm

1 m3 = 100 cm × 100 cm × 100 cm = 106 (or 1,000,000).

Question 2

A water tank is 3 m long 2…


📝 Question:

A water tank is 3 m long, 2 m broad and 1 m deep. What is the capacity of the tank (in litre) if 1 cubic m = 1000 lt? / 3 , 2 1 , 1 = 1000 ?

💡 Solution:

Length (l) = 3 m, Breadth (b) = 2 m, Depth (h) = 1 m

  • Volume of tank = l × b × h = 3 × 2 × 1 = 6 m3
  • Capacity in litres = 6 × 1000 = 6000 litres.

Question 3

If the length breadth and height of a…


📝 Question:

If the length, breadth and height of a tea box is 10 cm, 7 cm and 4 cm respectively then find its volume. / , 10 , 7 4 ,

💡 Solution:

Volume = l × b × h = 10 × 7 × 4 = 280 cm3

Question 4

The length breadth and height of a chalk…


📝 Question:

The length, breadth and height of a chalk box are 15 cm, 10 cm and 8 cm respectively. Find its volume. / , 15 , 10 8

💡 Solution:

Volume = l × b × h = 15 × 10 × 8 = 1200 cm3

Question 5

Find the volumes of the cuboidal shapes with…


📝 Question:

Find the volumes of the cuboidal shapes with given measurements /

💡 Solution:

(i) Length = 10 cm, Breadth = 5 cm, Height = 3 cm**

Volume = 10 × 5 × 3 = 150 cm3

(ii) Length = 4.5 cm, Breadth = 2.5 cm, Height = 2 cm

Volume = 4.5 × 2.5 × 2 = 22.5 cm3

(iii) Length = 8 m, Breadth = 4 m, Height = 2 m

Volume = 8 × 4 × 2 = 64 m3

(iv) Length = 5 m, Breadth = 3 m, Height = 1.5 m

Volume = 5 × 3 × 1.5 = 22.5 m3

(v) Length = 40 mm, Breadth = 35 mm, Height = 25 mm

Converting to cm: l = 4 cm, b = 3.5 cm, h = 2.5 cm

Volume = 4 × 3.5 × 2.5 = 35 cm3

(vi) Length = 60 mm, Breadth = 5 cm, Height = 4 cm

l = 60 mm = 6 cm

Volume = 6 × 5 × 4 = 120 cm3

(vii) Length = 12 cm, Breadth = 70 mm, Height = 20 mm

b = 70 mm = 7 cm, h = 20 mm = 2 cm

Volume = 12 × 7 × 2 = 168 cm3

(viii) Length = 1 m, Breadth = 25 cm, Height = 150 mm

l = 100 cm, b = 25 cm, h = 15 cm

Volume = 100 × 25 × 15 = 37500 cm3

SECTION / EXERCISE

EXERCISE 15.1 (Continued) / 15.1

(viii) Length = 1 m, Breadth = 25 cm, Height = 150 mm

  • Solution: Converting all measurements to cm:

Length (l) = 1 m = 100 cm

Breadth (b) = 25 cm

Height (h) = 150 mm = 15 cm

Volume = l × b × h = 100 × 25 × 15 = 37500 cm3

Question 6

The volume of a wooden cuboid is 480…


📝 Question:

The volume of a wooden cuboid is 480 cubic cm. Its length and breadth are 10 cm & 6 cm respectively. Find its height. / 480 10 6 ,

💡 Solution:

Height = (Volume)/(Length × Breadth) = (480)/(10 × 6) = 480/60 = 8 cm

Question 7

One side of a cube is 25 cm…


📝 Question:

One side of a cube is 25 cm. How many cubes of side 5 cm can be cut out from the given cube? / 25 5 ?

💡 Solution:

Volume of larger cube = 253 = 15625 cm3

  • Volume of smaller cube = 53 = 125 cm3
  • Number of cubes = (15625)/(125) = 125 cubes.

Question 8

The length breadth and height of a room…


📝 Question:

The length, breadth and height of a room are 5m, 4.5 m and 3 m respectively. Find the volume of air enclosed in the room. / , 5 , 4.5 3

💡 Solution:

Volume of air = 5 × 4.5 × 3 = 67.5 m3

Question 9

A cuboidal diesel tank is of length 2…


📝 Question:

A cuboidal diesel tank is of length 2 m, breadth 2m and depth 40 cm. Find its capacity in litres. / 2 , 2 40

💡 Solution:

l = 2 m, b = 2 m, h = 40 cm = 0.4 m

  • Volume = 2 × 2 × 0.4 = 1.6 m3
  • Capacity in litres = 1.6 × 1000 = 1600 litres.

Question 10

A swimming pool is 25 m long and…


📝 Question:

A swimming pool is 25 m long and 13 m broad. 325 cubic m water is poured into it. What will be the height of water in the pool? / 25 13 325 ?

💡 Solution:

Height = (Volume of water)/(Length × Breadth) = (325)/(25 × 13) = 325/325 = 1 m

Question 11

The edge of a cubical dice is 12…


📝 Question:

The edge of a cubical dice is 1.2 cm. Find its volume. / 1.2

💡 Solution:

Volume = S3 = (1.2)3 = 1.2 × 1.2 × 1.2 = 1.728 cm3

Question 12

A well is 8 m long 6 m…


📝 Question:

A well is 8 m long, 6 m broad and 9 m deep. It has water filled up to the height of 6 m. Find the capacity of the well and the present volume of water filled in the well. / 8 , 6 9 6

💡 Solution:

Total Capacity of well = 8 × 6 × 9 = 432 m3

  • Volume of water filled = 8 × 6 × 6 = 288 m3.

Question 13

A tank is 5 m long 4 m…


📝 Question:

A tank is 5 m long, 4 m wide and 3 m deep. Find the capacity of the tank. If the tank is filled with water upto 2 meters then find its volume. / 5 , 4 3 2 ,

💡 Solution:

Total Capacity = 5 × 4 × 3 = 60 m3

  • Volume of water = 5 × 4 × 2 = 40 m3 = 40000 litres.

Question 14

A brick is 20 cm long 10 cm…


📝 Question:

A brick is 20 cm long, 10 cm broad and 6 cm high. How many bricks will be required to make a wall 60 m long, 0.25 m wide and 2 m high? / 20 , 10 6 60 , 0.25 2 ?

💡 Solution:

Volume of 1 brick = 20 × 10 × 6 = 1200 cm3

  • Wall dimensions in cm: l = 6000 cm, b = 25 cm, h = 200 cm
  • Volume of wall = 6000 × 25 × 200 = 30,000,000 cm3
  • Number of bricks = (30,000,000)/(1200) = 25000 bricks.

SECTION / EXERCISE

EXERCISE 15.2 / 15.2

Question 1

Fill in the blanks


📝 Question:

Fill in the blanks /

💡 Solution:

(i) The total surface area of a cube of side 3 cm = ______ cm²**

TSA = 6S2 = 6(3)2 = 6 × 9 = 54 cm2.

(ii) The area of the front faces of the cuboid is _______________

The area of opposite faces of a cuboid is equal.

(iii) A cuboid with equal length, breadth and height is called a _________

A cuboid with equal length, breadth and height is called a cube.

Question 2

Find out the total surface area of the…


📝 Question:

Find out the total surface area of the cuboid whose length, breadth and height are 6.5 cm, 4.5 cm and 2 cm respectively. / , 6.5 , 4.5 2

💡 Solution:

TSA = 2(lb + bh + hl) = 2(6.5 × 4.5 + 4.5 × 2 + 2 × 6.5)

TSA = 2(29.25 + 9 + 13) = 2(51.25) = 102.5 cm2

Question 3

A cuboid has length 15 feet breadth 12…


📝 Question:

A cuboid has length 15 feet, breadth 12 feet and height 9 feet. Find its total surface area. / 15 , 12 9

💡 Solution:

TSA = 2(15 × 12 + 12 × 9 + 9 × 15) = 2(180 + 108 + 135) = 2(423) = 846 sq. feet

Question 4

Find the surface area of a cuboid whose…


📝 Question:

Find the surface area of a cuboid whose length is 0.5 m, breadth 25 cm and height 15 cm. / 0.5 , 25 15

💡 Solution:

Convert length to cm: l = 0.5 m = 50 cm, b = 25 cm, h = 15 cm

TSA = 2(50 × 25 + 25 × 15 + 15 × 50) = 2(1250 + 375 + 750) = 2(2375) = 4750 cm2

Question 5

Find the total surface area of cube having…


📝 Question:

Find the total surface area of cube having side 3.4 cm. / 3.4

💡 Solution:

TSA = 6S2 = 6(3.4)2 = 6 × 11.56 = 69.36 cm2

Question 6

Find the side of a cube whose total…


📝 Question:

Find the side of a cube, whose total surface area is 216 cm². / 216

💡 Solution:

6S2 = 216 ⇒ S2 = 216/6 = 36 ⇒ S = √36 = 6 cm

Question 7

The walls floor and roof of a room…


📝 Question:

The walls, floor and roof of a room are to be plastered. If the length, breadth and height of the room are 4.5 m, 3 m and 3.5 m respectively then calculate the area to be plastered. / , , 4.5 , 3 3.5 ,

💡 Solution:

Since all 6 faces (4 walls + floor + roof) are plastered, the required area equals the total surface area

Area = 2(4.5 × 3 + 3 × 3.5 + 3.5 × 4.5) = 2(13.5 + 10.5 + 15.75) = 2(39.75) = 79.50 m2

Question 8

The measurements of a cuboidal oil box are…


📝 Question:

The measurements of a cuboidal oil box are 30 cm, 40 cm and 50 cm respectively. The cost of the tin sheet used in making the box is Rs. 10 per m². Find the cost of the tin required to make 20 such boxes. / 30 , 40 50 10 20

💡 Solution:

Surface area of 1 box = 2(30 × 40 + 40 × 50 + 50 × 30) = 2(1200 + 2000 + 1500) = 9400 cm2 = 0.94 m2

  • Total surface area of 20 boxes = 20 × 0.94 = 18.8 m2
  • Total cost = 18.8 × 10 = Rs. 188.

Question 9

The edges of two cubes are 8 cm…


📝 Question:

The edges of two cubes are 8 cm and 4 cm respectively. Calculate the ratio of their surface area. / 8 4

💡 Solution:

Ratio = (6(8)2)/(6(4)2) = 64/16 = 4/1 = 4 : 1

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