Question

There are $20$ cylindrical pillars in a path. The radius of each pillar is $14cm$ and height $1m$. Find the cost of painting the curved surface of all the pillars at the rate of $Rs.10$ $per.sq.m.$

Answer 1

As we know that,

CSA of cylinder $=2\pi rh$

Radius of a pillar $=14cm=0.14m$

Height of pillar $=1m$

CSA of $1$ pillar $=2\times \frac{22}{7}\times 0.14\times 1=44\times 0.02=0.88m^2$

CSA of $20$ pillars $=0.88\times 20=17.6m^2$

Cost of painting per meter square $=Rs.10$

Therefore,

Cost of painting $17.6m^2=17.6\times 10=Rs.176$