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Question:

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

Solution:

Given: H=3.5m, R=50/2=25cm=25/100=0.25m
⇒CSA=2πrh=(2×22/7×0.25×3.5)m2=5.5m2
⇒Cost of painting 1m2 area=Rs.12.50
⇒Cost of painting 5.5m2 area=Rs.5.5×12.50=Rs.68.75