The radius of a roller is 49 cm and its length is 200 cm. It takes 700 complete rotations to level a playground once. Find the area of the playground. (Use π = 22/7)
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Correct answer: D
Explanation
The correct answer is option 4 i.e. 4312 × cm².
The radius of a roller, r = 49 cm
The length of the roller i.e., the height of the cylinder, h = 200 cm
[The distance covered by the roller in 1 revolution] = [Curved Surface Area of the cylinder] = 2πrh
⇒ The distance covered by the roller in 1 revolution is,
= 2 × 22/7 × 49 × 200 = 61600 cm²
Thus, the distance covered by the roller in 700 revolutions is given by,
= 700 × 61600 cm² = 4,31,20,000 cm² = 4312 × 104 m²