A cylindrical pillar is 50 cm in diameter and 3.5 m in height. Find the cost of painting the curved surface of the pillar at the rate of Rs 12.50 per m².

Radius of cylindrical pillar r = 50/2 = 25 cm = 0.25 m and height h = 3.5 m
Curved surface area of cylindrical pillar = 2πrh
= 2 × 22/7 × 0.25 × 3.5 = 2 × 22 × 0.25 × 0.5 = 5.5 m²
Cost of painting 1 m² area = Rs. 12.50
Therefore, cost of painting 5.5 m² area = Rs. 12.50 × 5.5 = Rs 68.75
Hence, the total cost of painting the cylindrical pillar is Rs 68.75.