Question 55

The height of a cone is 24 cm and radius of its base 10 cm.If the rate of painting it is ₹ 28/$$cm^2$$, then what will be the total cost in painting the cone from outside?

Solution

Height of cone = $$h=24$$ cm and radius = $$r=10$$ cm

=> Slant height = $$l=\sqrt{h^2+r^2}$$

=> $$l=\sqrt{576+100}=\sqrt{676}=26$$ cm

Curved surface area of cone = $$\pi rl$$

$$\therefore$$ Total cost of painting = $$28\times\frac{22}{7}\times10\times26$$

= $$Rs.$$ $$22,880$$

=> Ans - (D)

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