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 \({m}^{2}\).

Given :
Height (h) cylindrical pillar = 3.5 m
Radius (r) of the circular end of pillar = \(\frac{50}{2}\) cm = 25 cm = 0.25m

Now, we know that,
CSA of cylindrical pillar = \(2{\pi}rh\)
= \(2 × \frac{22}{7} × 0.25 × 3.5\) \({m}^2\)
= \(44 × 0.125\) \({m}^2\)
= 5.5 \({m}^2\)

Now, Cost of painting 1 \({m}^2\) area = Rs. 12.50
Cost of painting 5.5 \({m}^2\) area = Rs. (5.5 x 12.50) = Rs. 68.75

Therefore, the cost of painting the CSA of the pillar is Rs. 68.75