Question

A building has $25$ cylindrical shaped poles. Each has a radius of $28$ cm and a height of $4$ cm. Find the cost of painting curved surface of all poles at the rate of Rs. $8$ per $m^2$.

• A. $7.23$ Rs
  
• B. $8$ Rs
• C. $14.08$ Rs
• D. $56.32$ Rs

Answer 1

The correct option is C $14.08$ Rs

Given,

Radius of each pillar= 28 cm

Height of each pillar=4 cm

So, as we all know

CSA of a cylinder=$2\frac{22}{7}rh$

CSA of one pillar

$=2\frac{22}{7}\left(28\right)\left(4\right)$

$=704c{m}^2$ = $704\times {10}^{-4}{m}^2$

$=704\times {10}^{-4}\times \left(25\right)$

$=17600\times {10}^{-4}{m}^2$

Since, cost of painting 1 sq m= Rs. 8

∴Cost of 1.76 sq m =Rs. 8 ( 1.76)

= Rs. 14.08