Answer:
8488 miles
Step-by-step explanation:
The orbital period around an earth is given as:

Where G = constant = 6.67 x 10ˉ¹¹ N m² kgˉ², m = mass of object, T = period taken to round the earth, r = distance from the center of the earth to the orbiting object = radius of earth + orbital altitude.
Given that T = 7.84 hours = 28224 seconds, m = 5.972 x 10²⁴ kg, radius of earth = 3,958.8 miles = 6371071 m
![T=2\pi \sqrt{(r^3)/(Gm) }\\\\squaring:\\\\T^2=4\pi^2 ((r^3)/(Gm) )\\\\r^3=(GmT^2)/(4\pi^2) \\\\r=\sqrt[3]{(GmT^2)/(4\pi^2) } \\\\r=\sqrt[3]{(6.67*10^(-11)*5.972*10^(24)*(28224)^2)/(4\pi^2) } \\\\r=20031232.62\ meters](https://img.qammunity.org/2021/formulas/physics/college/fq6705lb6c6ic59uanjwcy4jjefw3rz1ea.png)
r = radius of earth + distance from the ISS to the surface of the earth
distance from the ISS to the surface of the earth = r - radius of earth
distance from the ISS to the surface of the earth = 20031232.62 meters - 6371071 meters = 13660161.62 meters
distance from the ISS to the surface of the earth = 13660161.62 meters = 8488 miles