\({I}={I}_{{CM}}+{Md}^{2}\)
\({I}=\frac{{Mr}^{2}}{2}+{M}\left(\frac{{L}}{2}\right)^{2}\)
\(2.7={M} \frac{(0.2)^{2}}{2}+{M}\left(\frac{0.8}{2}\right)^{2}\)
\(2.7={M}\left[\frac{2}{100}+\frac{16}{100}\right]\)
\({M}=15\, {kg}\)
\(\Rightarrow \rho=\frac{{M}}{\pi {r}^{2} {L}}=\frac{15}{\pi(0.2)^{2} \times 0.8}\)
\(=0.1492 \times 10^{3}\)