Mass \(=\) Density\(\times\)Volume

Let \(d\) be the density of both the iron plate

Using the above equations,

\(I_{A}=(d)\) \(\times\) \(\Pi r^{2} t \frac{r^{2}}{2}=\frac{\Pi d t r^{4}}{2}\)

\(I_{B}=d\) \(\times\) \(\Pi(4 r)^{2} \frac{t}{4} \frac{(4 r)^{2}}{2}=64 I_{A}\)

Moment Of Inertia \(=I=\frac{M R^{2}}{2}\)

Mass \(=\) Density\(\times\)Volume

Let \(d\) be the density of both the iron plate

Using the above equations,

\(I_{A}=(d)\) \(\times\) \(\Pi r^{2} t \frac{r^{2}}{2}=\frac{\Pi d t r^{4}}{2}\)

\(I_{B}=d\) \(\times\) \(\Pi(4 r)^{2} \frac{t}{4} \frac{(4 r)^{2}}{2}=64 I_{A}\)

Therefore, \(I_{A} < I_{B}\)