Question

It takes 2 liters to paint the surface of a solid sphere. If this solid sphere is sliced into 4 identical pieces, how many liters will be required to paint all the surfaces of these 4 pieces.

Accepted Answer

D. Surface area of full sphere = $4\pi r^2$, requiring 2 liters. Cutting into 4 identical pieces (quarter spheres) creates 4 internal circular flat surfaces of area $\pi r^2$ each, i.e., an additional $4\pi r^2$ surface area. Total new surface area = $4\pi r^2 + 4\pi r^2 = 8\pi r^2$, which is double the original. Thus, paint required = $2 	imes 2 = 4.0$ liters.

Surface Area of Cut Sphere

Explanation

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