Solve this

Question:

Note Use $\pi=\frac{22}{7}$, 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.

 

Solution:

Slant height of the conical tomb, l = 25 m

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

$\therefore$ Curved surface area of the conical tomb $=\pi r l=\frac{22}{7} \times 7 \times 25=550 \mathrm{~m}^{2}$

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.

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