Total moment of inertia

\(= I _1+ I _2+ I _3+ I _4=2 I _1+2 I _2\)

\(=2\left( I _1+ l _2\right)\left[ I _3= I _1, I _1= I _4\right]\)Now, \(I _2= I _3=\frac{ Ml ^2}{3}\)

Using parallel axes theorem, we have

\(I = I _{ CM }+ Mx ^2 \text { and } x =\sqrt{l^2+\frac{l^2}{4}}\)

\(I _1= I _4=\frac{ M l^2}{12}+ M \left[\sqrt{l^2+\left(\frac{l}{2}\right)^2}\right]^2\)

Putting all values we get

Moment of inertia, \(I =10\left(\frac{ Ml ^2}{3}\right)\)