Question

The inner diameter of a circular well is 3.5 m and it is 12 m deep. Find the cost of plastering the inner surface at the rate of Rs.4 per square metre.

Answer 1

CSA=2πrh
2×22/7×1.75×12=132
Cost of plastering=132×4=₹528

Answer 2

Diameter of well internally=3.5m

radius of well=3.5/2 m
height of well=12m
CSA of well internally=2*22/7*3.5/2*12=132 m^2
rate of painting=rs4/m^2
total cost=132*12=rs1584