Question

the diameter of a roller is 84 cm and its length is 20 cm. It takes 1000 complete revolutions to move once over to level a playground.find the area of the playground in metre square

plz answer fast ​

Answer 1

Given:-

• Diameter of the roller = 84 cm
• Length of the roller = 20 cm
• It takes 1000 revolutions to move once over to level a playground.

To Find:-

The area of the playground.

Solution:-

Firstly we need to find the radius of the roller.

$\sf{Diameter = 84\:cm}$

$\sf{Radius = \dfrac{Diameter}{2}}$

= $\sf{Radius = \dfrac{84}{2}}$

= $\sf{Radius = 42\:cm}$

Now let us convert the values of length and radius of the roller into m

$\sf{Radius = 42\:m = \dfrac{42}{100} = 0.42\:m}$

$\sf{Length = 20\:cm = \dfrac{20}{100} = 0.2\:m}$

Now,

Let us calculate the CSA of the Roller,

$\sf{CSA = 2\pi r l}$

= $\sf{CSA = 2\times \dfrac{22}{7}\times 0.42\times 0.2}$

= $\sf{CSA = 5.28\:m^2}$

As The Roller takes 1000 complete revolutions of the ground, The area of the ground will be:-

$\sf{CSA\:of\:roller\times 1000}$

$\sf{Area\:of\:playground = 5.28\times 1000}$

$\sf{Area\:of\:playground = 5280\:m^2}$

Therefore the Area of the playground is 2640 m².

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$\bf{\underline{\underline{Formula\:Used!!!}}}$

Curved Surface Area of the roller = πrh sq.units

Note:-

CSA = Curved Surface Area.

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Answer 2

Answer:

$\huge \bold{ \underline{Given:-}}$

• Diameter of the roller=84m
• Diameter of the roller=84mLength of the roller=20cm
• Diameter of the roller=84mLength of the roller=20cmIt takes 1000 Revolutions to move once over to level the playground

$\huge \bold{ \underline{To \: Find:-}}$

The area of the playground

$\huge \bold{ \underline{Solution:-}}$

$Diameter=d= 84cm$

$radius = \frac{Diameter}{2}$

$radius = \frac{84}{2} = 42cm$

Now let us convert the value of length and radius into m.

$Radius=42cm = \frac{42}{100} = 0.42m$

$length = 20cm = \frac{20}{100} = 0.2m$

Now,

Let us calculate the CSA of roller.

$CSA = 2\pi rl$

$= 2 \times \frac{22}{7} \times 0.42 \times 0.42m$

$CSA = 5.28 {m}^{2}$

As the roller takes 1000 complete revolution of the ground ,The area of the ground will be:-

$CSA \: of \: roller \times 1000$

$Area \: of \: playground = 5.28 \times 1000$

$Area \: of \: playground = 5280 {m}^{2}$

$\therefore \: the \: area \: of \: playground \: is 5280 {m}^{2}$

Step-by-step explanation:

Hope it helps you