Question

$10$ cylindrical pillars of building have to be painted.If the diameter of each pillar is $50$m and the height is $4$m.Find the cost of painting at the rate of Rs.$7$ per square metre.

• A. Rs.$44,000$
• B. Rs.$4400$
• C. Rs.$440$
• D. Rs.$44$

Answer 1

The correct option is

B

Rs.$44,000$

Diameter of the pillar$=50$ m

Radius$=25$ m

Height$=4$ m

$\therefore$ Curved surface area of a pillar$=2\pi rh=2\times \frac{22}{7}\times 25\times 4m^2$

Curved surface area of $10$ pillars$=2\times \frac{22}{7}\times 25\times 4\times 10m^2$

Cost of painting$=$Rs.$7$per sq.m

$\therefore$ Total cost of painting $10$ pillars$=2\times \frac{22}{7}\times 25\times 4\times 10\times 7$

$=$Rs.$44,000$