At what height above the surface of the Earth will the acceleration of gravity be η = 30% of the acceleration

At what height above the surface of the Earth will the acceleration of gravity be η = 30% of the acceleration of gravity on the surface of the Earth?

Free fall acceleration on the Earth’s surface
g1 = G * Мз / Rз².

Acceleration of gravity at a distance from the center of the Earth
g2 = G * Мз / Rх².

Let’s compose the equation of the acceleration ratios and find the height from the center of the Earth
g2 / g1 = (G * Мз / Rх²) / (G * Мz / Rх²) = RЗ² / Rх² = η / 100;

Rх² = 100 * Rз² / η;
Rх = √ (100 * Rз² / η) = Rз * √ (100 / η) = 6170 * 1.826 = 11265 km.

Distance from the surface of the Earth
Rп = Rх – Rз = 11265 – 6170 = 5095 km.

Answer: at an altitude of 5095 km from the surface of the Earth.