Question

a cylindrical wall is 21 m deep its outerand inner diameters are 21m and 14 m respectively find the cost of renovating the inner curved surface and outer curved surface at the rate of ₹25 per m2

Answer 1

CSA of inner side + CSA of outer side
2πrh+ 2πRh
2πh(r+R)
2×22/7×21(7+10.5)
528m^2
cost of renovating 1m^2 area = Rs.25
cost of renovating 528m^2 area = Rs.25×528
Rs.13,200