Solution to 1992 Problem 19

The universal gravitational constant
\begin{align*}G = 6.67 \cdot 10^{-11} \;\mathrm{m}^3\mathrm{/}\mathrm{(}\mathrm{kg}\;\mathrm{s}^2)\end{align*}
is given at the beginning of the exam. So, use
\begin{align*}g = \frac{MG}{R^2}\end{align*}
and the known value of g = 9.8 \;\mathrm{m}\mathrm{/}\mathrm{s}^2 to estimate M. The result is
\begin{align*}M \approx \boxed{6 \cdot 10^{24} \mbox{ kg}}\end{align*}

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