Question

Note Use $\mathrm{\pi }=\frac{22}{7}$, unless stated otherwise.
The slant height and base diameter of a conical tomb are 25 m and 14 m respectively. Find the cost of whitewashing its curved surface at the rate of ₹ 12 per m².

Answer 1

Slant height of the conical tomb, l = 25 m

Radius of the conical tomb, r = $\frac{14}{2}$ = 7 m

∴ Curved surface area of the conical tomb = $\mathrm{\pi }rl=\frac{22}{7}\times 7\times 25$ = 550 m²

Rate of whitewashing = ₹ 12 per m²

∴ Cost of whitewashing the conical tomb

= Curved surface area of the conical tomb × Rate of whitewashing

= 550 × 12

= ₹ 6,600

Thus, the cost of whitewashing the conical tomb is ₹ 6,600.