#### Answer

The locus of points that are midpoints of the radii of the larger sphere includes all the points on the surface of the sphere with the same center of $O$ and a radius of 2.5 m.

#### Work Step by Step

The locus of points that are midpoints of the radii of the larger sphere includes all the points on the surface of the sphere with the same center of $O$ and a radius of 2.5 m.
Since the larger sphere has a radius of 5 m, the smaller sphere has a radius of 2.5 m.
The sketch shows a cross-section of the two spheres, with the smaller sphere embedded symmetrically inside the larger sphere.