A=[ay]2×2 and entries are 0 or 1. $\begin{aligned}
& \therefore\left|\begin{array}{ll}
a & b \
c & d
\end{array}\right|=0 \
& \Rightarrow a d-b c=0
\end{aligned}CaseI:a d=b c=1\therefore \quad a=b=c=d=1CaseII:a d=b c=0\begin{array}{ll}
a=0, d=0 & b=0, c=0 \
a=0, d=1 & b=0, c=1 \
a=1, d=0 & b=1, c=0
\end{array}\thereforeTotal10caseswhenmatrixisnoninvertibleTotalpossiblematrix=2^4=16Requiredprobabilityofinvertible=\frac{16-10}{16}=\frac{6}{16}=\frac{3}{8}$