The radius of a roller is 49 cm and its length is 200 cm . It takes 700 complete revolutions to move once over to level a playground. Find the area of the playground.

(Use \(\pi=\frac{22}{7}\).)

Question

Question

This question was previously asked in

SSC CHSL Exam 2024 Tier-I Official Paper (Held On: 01 Jul, 2024 Shift 3)

Answer 1

Given:

Radius of roller (r) = 49 cm

Length of roller (h) = 200 cm

Number of revolutions (n) = 700

Use π = 22/7

Concept:

The area covered by the roller in one revolution is the lateral surface area of the cylinder.

Formula Used:

Lateral Surface Area of Cylinder = 2πrh

Total Area = Lateral Surface Area × Number of Revolutions

Calculation:

We have,

⇒ r = 49 cm, h = 200 cm, π = 22/7

⇒ Lateral Surface Area = 2 × (22/7) × 49 × 200

⇒ Lateral Surface Area = 2 × 22 × 49 × 200 / 7

⇒ Lateral Surface Area = 2 × 22 × 7 × 200

⇒ Lateral Surface Area = 2 × 22 × 1400

⇒ Lateral Surface Area = 61600 cm²

⇒ Total Area = 61600 × 700

⇒ Total Area = 43120000 cm²

∴ The area of the playground is 4312 × 10⁴ cm².

Hence, the correct answer is option 2.

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