Answer
This ball is a hollow sphere.
Work Step by Step
Let's assume,
mass of the ball = M
Radius of the ball = R
Speed of the ball = V = $r\omega$
We can write,
Translational kinetic energy $(K_{1})= \frac{1}{2}MV^{2}$
Rotational kinetic energy $(K_{2})= \frac{1}{2}I\omega^{2}$
$K_{2}=\frac{1}{2}I\frac{V^{2}}{R^{2}}-(1)$
Given that, Total kinetic energy $(K)=K_{1}+K_{2}=100\space J-(2)$
$K_{2}=40\space J-(3)$
$(2)=\gt (1)$
$K_{1}=100\space J-40\space J=60\space J$
$ \frac{1}{2}MV^{2}=60=\gt V^{2}=\frac{120}{M}$
$(3)=\gt (1)$
$40=\frac{1}{2R^{2}}I\times\frac{120}{M}$
$I=\frac{2}{3}MR^{2}$
This equation is equal to the rotational inertia of a hollow sphere. So this ball is a hollow sphere