Correct Answer - Option 1 : Rs. 471

**Given:**

Diameter of each pillar = 0.4 m

∴ Radius of each pillar = r = 0.4/2 = 0.2 m

Height of the each pillar = 5 m

**Formula used:**

Area of cylinder = 2πrh

**Calculation:**

Curved surface area of each pillar = 2πrh

⇒ 2 × 3.14 × 0.2 × 5

⇒ 6.28 m^{2}

Therefore, curved surface area of 25 pillar = 6.28 × 25 = 157 sq. m

Cost of cleaning = Rs. 3 per sq. m

∴ Cost of cleaning 25 pillars = Rs. 3 × 157

⇒ Rs. 471