A hollow spherical shell has an external diameter of 36 cm and an internal diameter of 28 cm. It is melted and recast into spherical balls, each of radius 2 cm. Find the total number of balls formed and the total surface area of all the balls formed.
A.309, 6512π cm²
B.378, 6456π cm²
C.386, 6176π cm²✓ Correct
D.314, 6670π cm²
Explanation
Volume of shell = (4/3)π(18³−14³) = (4/3)π×3088. Each small ball volume = (4/3)π(2)³, so n = 3088/8 = 386 balls. Total surface area = 4π(2)²×386 = 6176π cm².
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