Question

In a building there are $30$ cylindrical pillars. The radius of each pillar is $35	ext{ cm}$ and height is $5	ext{ m}$. Find out the cost of painting the curved surface of half the number of pillars. The rate of painting is Rs. $10	ext{ per m}^2$.

Accepted Answer

C. Base radius $r = 35	ext{ cm} = 0.35	ext{ m}$, height $h = 5	ext{ m}$. Curved Surface Area (CSA) of $1$ pillar $= 2\pi r h = 2 	imes \frac{22}{7} 	imes 0.35 	imes 5 = 11	ext{ m}^2$. Half the number of pillars $= 15$. Total CSA for 15 pillars $= 15 	imes 11 = 165	ext{ m}^2$. Total cost $= 165 	imes 10 = 	ext{Rs. } 1650$.

Cost of painting pillars

Explanation

Practise this under exam conditions