Riya use a cylindrical paint roller to paint wall and ceiling of a room with dimensions 21 metre × 10 metre × 35 metre . if the height of cylinder is 70 cm and its diameter is 100 cm. find the minimum number of times she needs to roll the paint roller in order to paint a room
Answers
mensuration
Mensuration is the branch of mathematics which concerns itself with the measurement of Lengths, areas & volume of different geometrical shapes or figures.
Surface area:
The surface area of a solid is the sum of the areas of the plane and curved faces of the solid.
It is measured in square units such as square centimetre (cm²) and square metre (m²).
Surface area of cuboid is the sum of the surface areas of its six rectangular faces.
Surface Area of Cuboid is =
2(lb + lh + bh)
By surface area of a cuboid we mean the total surface area.
The sum of the areas of 4 vertical faces of a cuboid is called its lateral surface area.
The lateral surface area or the area of the four walls of the cuboid .
Area of the four walls = 2 (l +b) h
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Solution:
Given;
Length of wall (l)= 15 m, Breadth of wall (b)= 10 m Height of wall (h) = 7 m
Total area to be painted= area of 4 walls + area of ceiling
= 2(l+b)h + lb
= 2(15+10)7 + 15×10
= 2×25×7+ 150
=50× 7+150= 350+ 150=500
Total area to be painted=500m²
Given 100m² area can be painted from each can.
Number of cans Required=
Area of hall/ area of 1 can
= 500/100= 5
Hence, 5 cans are required to paint the room.
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