Volume Of A Combination Of Solids

A solid which is bounded by six rectangular faces is known as cuboid and if the length, breadth and height of the cuboid are equal, then it is a cube.

8 vertices, 6 faces and 12 edges are there in both cube as well as cuboid. Base of the cuboid is any face of the cuboid.

For a cuboid which has length (l), breadth (b) and height (h) has:

  • Volume = l×b×h
  • Total surface area = 2(lb+bh+lh)

For a cube with length x,

  • Volume = x3 (because l = b = h = x)
  • Total surface area = 6x2

Volume of combination of solids Examples:

Q1. For a room of dimension 10m×8m×9m.Find out the longest pole that can be put in this room.

Solution: Longest pole is the longest diagonal of the room= √(102+92+82)

= √245


The longest pole that can be put inside the room has length=15.652m.

Q2. A cube has a volume 343cm3.Find the surface area of the cube.

Solution: The volume of the cube=a3=343

a = 3√343 = 7

Total surface area=6a2


Total surface area of the cube=294cm2

Q.3. A cuboidal water tank is aluminium steel sheet which is 4.5m thick. The outer dimensions are 1.5m×2.5m×3m. Find the internal dimensions and total surface area of the tank.

Solution: External dimensions of the cube are:

l=150cm, b=250cm and h=300cm.

As we know that the sheet is 4.5m thick, the internal dimensions are:



H= (300-9) =291cm

Total surface area of the tank=2(lb+bh+lh)


=31.5 m3.

Q.4. How many tissue boxes of size 10cm×8cm×9cm can be adjusted inside a cupboard box of size 36cm×40cm×100cm.

Solution: Volume of the tissue box = 10 x 8 x 9 cm3


Volume of the cupboard = 36 x 40 x 100 cm3.


Combination Of Solids

=200 boxes

Therefore we can say that 200 tissue boxes can be adjusted in the cupboard box. For more information contact byju’s mentors.

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