A set is a well-defined collection of objects. Each object in a set is called an element of the set. Two sets are equal if they have exactly the same elements in them.
A set is a subset of another set if all elements of the set are elements of the set . In other words, the set is contained inside the set . The subset relationship is denoted as A ⊂ B .The relationship of one set being a subset of another is also called inclusion or we can say Set B may have more elements than A does.
Option 4 .Set B may have more elements than A does is the right answer.
If you crumble paper it is hard to uncrumble like trust
Note: The height of the room must be 3 m instead of 3 cm because 3 cm is too small and it cannot be the height of a room.
Given:
Perimeter of the floor of a room = 18 metre
Height of the room = 3 metre
To find:
The area of 4 walls of the room.
Solution:
We know that, the area of 4 walls of the room is the curved surface area of the cuboid room.
The curved surface area of the cuboid is

Where, h is height, l is length and b is breadth.
Perimeter of the rectangular base is 2(l+b). So,

Putting the given values, we get


Therefore, the area of 4 walls of the room is 54 sq. metres.
5.6 x 2.1 x 6.6 = 77.616 2 significant figures would be 78 cm³ 2 decimal places would be 77.62 cm³
ANSWER
My answer is in the photo above