Question

in a building there are 24 cylindrical pillars.the radius of each pillar is 28cm and cost of painting the pillars at the rate of ₹8 per square metre​

Answer 1

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