Question

Diameter and length of a roller are 84 cm and 120 cm respectively. In how many revolutions, can the roller level the playground of area 1,584 m??​

Answer 1

Answer:

Answer of this question is 500 revolutions.

Step-by-step explanation:

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Answer 2

To find :

In how many revolution , the roller can level the playground.

Given :

• diameter of the roller = 84 cm
• length of the roller = 120 cm
• area of the playground = 1584 m²

Formula to be used:

• CSA of cylinder = 2pi rh
• 1 m² = 10000 cm²

Solution :

1 m² = 10000 cm²

$\implies \bold{1584 {m}^{2} = 10000 \times 1584 {cm}^{2} } \\ \implies \bold{1584 {m}^{2} = 15840000 {cm}^{2} }$

CSA of the cylinder

$= \bold{2 \pi \: rh} \\ = \bold{2 \times \frac{22}{7} \times 42 \times 120} \\ = \bold{2 \times 22 \times 6 \times 120} \\ = \bold{31680 \: c {m}^{2} }$

hence, total number of revolution needed

= 15840000/31680

= 500 revolution

hence, 500 revolution is needed