Question

the diameter of a 120 cm long roller is 84 cm It takes 1000 complete revolutions in moving once over to level a playground what is the area of the playground​

Answer 1

★Solution :

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➪ Length of roller = 120 cm.

➪ Diameter of roller = 84 cm.

➪ Radius of roller = $\dfrac{(Diameter)}{2}$

= $\dfrac{84}{2}$

= 42 cm

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As we know, a roller is in the shape of cylinder.

➪Perimeter of roller = Area covered by roller in 1 one revolution = 2 × π × (radius ) × length

➪Perimeter = 2×( $\dfrac{22}{7}$ ) × 42 × 120

➪Perimeter = 44 × 6 × 120

➪Perimeter = 31,680 cm²

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Therefore,

➪Area covered by wheel in 1000 revolutions

= (31,680×1000) cm²

= $\dfrac{31,680,000}{10000}$

Answer = 3,168m²

Hence, Area of Playground is 3,168m²

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Answer 2

Step-by-step explanation:

Radius of the roller (r)=

2

84

cm=42cm

length of the roller (h)=120cm

∴ Area of the playground levelled in taking 1 complete revolution 2πrh

=2×227×42×120=31680cm

2

∴ Area of the playground

=31680×500=15840000cm

2

100×100

15840000

m

2

=1584m

2