Answer
The distance of the center of mass of the Earth-Moon system (from the center of the Earth) is $~~72.8\%~~$ of the Earth's radius.
Work Step by Step
The Earth's radius is $~~6.37\times 10^6~m$
In part (a), we found that the center of mass of the Earth-Moon system is a distance of $~~4.64\times 10^6~m~~$ from the center of the Earth.
We can express this distance as a percentage of the Earth's radius:
$\frac{4.64\times 10^6~m}{6.37\times 10^6~m}\times 100\% = 72.8\%$
The distance of the center of mass of the Earth-Moon system (from the center of the Earth) is $~~72.8\%~~$ of the Earth's radius.
