21.In a building, there are 24 cylindricalpillars. The radius of each

1.	21.In a building, there are 24 cylindricalpillars. The radius of each pillar is 28 cmand height is 4 m. Find the total cost ofpainting the curved surface area of allpillars at the rate of 8 per m2(A) 1352.68 (B) 351.68(C) 1353.68 (D)1340.68
Answer» Radius of cylinderical pillars = r = 28cm =0.28m height ,h=4m curved surface area of a cylinder =2πrh curved surface area of a pillar= 2×22\6×0.28×4=7.04metresq. Curved surface area of 24 such pillars = 7.04×24=168.96metresq. cost of cementing an area of 1metresq. =Rs8 so,cost of painting 1689.6metresq. =168.96×8=Rs1,351.68 Like my answer if you find it useful!

21.In a building, there are 24 cylindricalpillars. The radius of each pillar is 28 cmand height is 4 m. Find the total cost ofpainting the curved surface area of allpillars at the rate of 8 per m2(A) 1352.68 (B) 351.68(C) 1353.68 (D)1340.68

Answer»

Radius of cylinderical pillars = r = 28cm =0.28m

height ,h=4m

curved surface area of a cylinder =2πrh

curved surface area of a pillar= 2×22\6×0.28×4=7.04metresq.

Curved surface area of 24 such pillars = 7.04×24=168.96metresq.

cost of cementing an area of 1metresq. =Rs8

so,cost of painting 1689.6metresq.

=168.96×8=Rs1,351.68

Like my answer if you find it useful!