Q.

Let S={M=[aij],aij∈{0,1,2},1≤i,j≤2} be a sample space and A={M∈S:M is invertible} be an event. Then P(A) is equal to        [2023]

1 5081  
2 4781  
3 4981  
4 1627  

Ans.

(1)

Let M=[pqrs]    where p,q,r,s∈{0,1,2}

n(S)=34=81

First, we find p(A¯)

A¯={M∈S:|M|=0}

|M|=0⇒ps=qr

ps=qr=0⇒number of (p,q,r,s)=(32-22)2=25

ps=qr=1⇒number of (p,q,r,s)=12=1

ps=qr=2⇒number of (p,q,r,s)=22=4

ps=qr=4⇒number of (p,q,r,s)=12=1

P(A¯)=3181⇒P(A)=5081