A cylindrical pillar is 50 cm in diameter and 3.5 m in height.

Height (h) cylindrical pillar = 3.5 m

Radius (r) of the circular end of pillar 

= 50/2 cm =25cm = 0.25m

CSA of pillar = 2πrh

= (2 x 22/7 x 0.25 x 3.5)m²

= (44 x 0.125)m² = 5.5m²

Cost of painting 1 m² area = Rs 12.50

Cost of painting 5.5 m² area = Rs (5.5 × 12.50) = Rs 68.75

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

Height of cylindrical pillar (h) = 3.5 m 

Radius of circular end of pillar ( r) = 50/2 cm 

= 25 cm 

= 0.25 m [As radius = half of the diameter] and [1 m = 100 cm] 

Curved surface area of cylindrical pillar = 2πrh 

= 2 x 3.14 x 0.25 x 3.5 

= 5.5 

Curved surface area of cylindrical pillar is 5.5 m.

Cost of whitewashing 1m² is Rs 12.50

Cost of whitewashing 5.5 m² area = Rs. 12.50 x 5.5 

= Rs. 68.75 

Thus the cost of whitewashing the pillar is Rs 68.75.