Given:H=3.5 m, R=250​=25 cm =10025​=0.25 m⇒CSA=2πrh=(2×722​×0.25×3.5) m2=5.5 m2⇒Cost of painting 1 m2 area = Rs.12.50⇒Cost of painting 5.5 m2 area = Rs.5.5×12.50= Rs.68.75