Question

The diameter of a roller is 84 cm and its length is 120 cm. The roller takes 150 complete revolution to move

once over a playground to level it. Find the area of the playground in square meter​

Answer 1

Answer:

• first we will find out the area of roller -->2pie rh
• 2 into 22/7 into 42 into 120 =31680 cm²
• now we will find out the area of 150 round
• 150 into 31680 = 4752000
• area in square meters = 4725000/100
• =47250m²ans

Answer 2

Given :

• Diameter of Roller is 84 cm .
• Length of Roller is 120 cm .

To Find :

• Area of the playground in m² .

Solution :

Firstly we will Find Area of 1 revolution :

$\longmapsto\tt{Radius=\cancel\dfrac{42}{2}=21\:cm}$

$\longmapsto\tt{Length\:or\:Height=120\:cm}$

Using Formula :

$\longmapsto\tt\boxed{C.S.A\:of\:Cylinder=2\pi{rh}}$

Putting Values :

$\longmapsto\tt{2\times\dfrac{22}{{\cancel{7}}}\times{{\cancel{42}}}\times{120}}$

$\longmapsto\tt{44\times{6}\times{120}}$

$\longmapsto\tt\bf{31680\:{cm}^{2}}$

Now ,

$\longmapsto\tt{Area\:of\:500\:Revolutions=31680\times{500}}$

$\longmapsto\tt\bf{15840000\:{cm}^{2}}$

In m² :

$\longmapsto\tt{\dfrac{1584{\not{0}}{\not{0}}{\not{0}}{\not{0}}}{1{\not{0}}{\not{0}}{\not{0}}{\not{0}}}}$

$\longmapsto\tt\bf{1584\:{m}^{2}}$

So , The Area of Ground is 1584 m² ..

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• 1 m = 100 cm
• 1 m² = 10000 cm
• C.S.A of Cylinder = 2πrh
• T.S.A of Cylinder = 2πr(r+h)
• Volume of Cylinder = πr²h

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