Passage III
Earth's gravitational field extends both above and below Earth's surface. In Figure 1, both the value of this field, 
, and the average density, ρ, of matter within Earth are graphed versus distance, r, from Earth's center. In addition, Figure 1 identifies 5 regions, each of which is located either above or below Earth's surface.
Figure 2 shows the percent of Earth's mass located within a given distance r from Earth's center. For example, 10% of Earth's mass is located within 2,300 km of Earth's center, 20% of Earth's mass is located within 2,900 km of Earth's center, and so on.
16. Figures 1 and 2 indicate that Earth’s radius is approximately:
Your Answer is
Correct Answer is J
Explanation
Note that the Earth's radius asked in the question should only include core, mantle, and crust, but not the thickness of the atmosphere.
So according to figures 1 & 2, it can be seen that the radius of the earth is about 6400 km