Answer
r=9.0cm
Work Step by Step
density=$\frac{mass}{volume}=\frac{m}{v}=19.5g/cm^{3}$
$m_{critical}$=60.0kg
Volume of sphere=v=$\frac{4}{3}πr^{3}$
v=$\frac{m_{critical}}{density}=(\frac{60.0kg}{19.5g/cm^{3}})(\frac{1000g}{1.0kg})=3080cm^{3}$
r=$\sqrt[3] \frac{3v}{4π}$=$\sqrt[3]\frac{3(3080cm^{3})}{4π}$=9.0 cm
