Question

A building has 8 right cylindrical pillars whose cross sectional diameter is 1 m and whose height is 4.2 m. Find the expenditure ot paint these pillars at the rate of Rs. 24 per m².

Answer 1

Radius of the cylindrical pillar = $\frac{\mathrm{Diameter}}{2}=\frac{1}{2}=0.5\mathrm{m}$
Height of the cylindrical pillar = 4.2 m

Curved surface area of 1 cylindrical pillar = 2$\mathrm{\pi }$rh
= 2 × $\frac{22}{7}$ × 0.5 × 4.2
= 13.2 m²
Curved surface area of 8 cylindrical pillars = 13.2 × 8
=105.6 m²
Cost of painting 1 m² area of pillar = Rs 24
Cost of painting 105.6 m² area of pillars = 24 × 105.6
= Rs 2534.40