El volumen de una esfera es: [tex]V = \frac{4}{3}\pi \cdot R^3[/tex]
a) [tex]V = \frac{4}{3}\pi \cdot (5+\frac{2}{3})^3 = \frac{4\pi}{3}\cdot (181+\frac{26}{27}) = \bf 762,2\ cm^3[/tex]
b) Despejando el radio: [tex]R = \sqrt[3]{\frac{3V}{4\pi}}[/tex]
[tex]R = \sqrt[3]{\frac{3\cdot 36\pi\ cm^3}{4\pi}} = \bf 3\ cm[/tex]