Answer
The acceleration of gravity 380 km above the earth's surface is only about 11% weaker than at the Earth's surface.
Work Step by Step
Let's use 6380 km as the radius of the Earth. At 380 km above the Earth's surface, $r = 6.76 \times 10^6 ~m$. Therefore,
$\frac{GM}{r^2} = \frac{(6.67 \times 10^{-11}~N\cdot m^2/kg^2)(5.98 \times 10^{24}~kg)}{(6.76 \times 10^6 ~m)^2}$
$\frac{GM}{r^2} = 8.7 ~m/s^2$
We know that $g = 9.8 ~m/s^2$ near the Earth's surface.
We can find the difference in percent.
$\frac{(9.8 ~m/s^2)-(8.7 ~m/s^2)}{9.8 ~m/s^2}\times 100\% = 11\%$
The acceleration of gravity 380 km above the Earth's surface is only about 11% weaker than at the Earth's surface.
