Question 75

The height of a right circular cone is 24 cm and the radius of its base is 7 cm. What is the cost of painting the curved surface area of the cone at the rate of ₹6 per cm$$^2$$? (Take $$\pi$$=$$\frac{22}{7}$$)

Solution

r= 7 cm

Curved surface area of cone =$$\pi \times r \times l $$

l = $$\sqrt{r^2 +h^2} = 24^2+7^2 = 576+49 = \sqrt{625}$$

= 25 cm

Curved surface area of cone =$$\pi \times 7\times 25$$

= 550 $$cm^2$$

Given ,rate = ₹6 per cm$$^2$$

= $$550\times 6$$

= Rs3300

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