The height at which the satellite is situated, h=320 km=320×10³ m
The acceleration due to gravity at a height h is given by,

Where R is the radius of the earth and g is the acceleration due to gravity at the surface of the earth.
The radius of the earth is 6.37×10⁶ m.
On substituting the known values in the above equation,

Thus the ratio of the acceleration due to gravity at the given height to that at the surface of the earth is 0.9