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Question:

The inner diameter of a circular well is 3.5 m. It is 10 m deep. Find (i) its inner curved surface area (ii) the cost of plastering the curved surface at the rate of Rs. 40 per m²

Solution:

Given:
→(i)r=radius=3.5/2=1.75, h=depth of the well=10m
→Curved surface area=2πrh=(2×22/7×1.75×10)m²=110m²
→(ii) Cost of plastering=Rs40 per m²
The cost of plastering the curved surface=Rs(110×40)=Rs4400.