Question

Twenty cylindrical pillars of the Parliament House are to be cleaned. If the diameter of each pillar is 0.50 m and height is 4 m. What will be the cost of cleaning them at the rate of Rs. 2.50 per square metre? 

Answer 1

Diameter of each pillar=`0.5m` 

Radius of each pillar` (r) a/2= 0.5/2=0.25m `

Height of each pillar=4m 

Curved surface area of each pillar=`2pirh` 

= `2xx3.14xx0.25xx4m^2` 

=` 44/7 m^2` 

Curved surface area of 20 pillars= `20xx44/7m^2` 

Given, cost of cleaning= Rs.2.50 per square meter 

∴Cost of cleaning 20 pillars = `Rs.2.50xx20xx44/7` 

=Rs.314.28.