A die is thrown repeatedly until a six occurs.

Since number of times is not mentioned the sample space will be infinite.

$\therefore$ The sample space

$S=\left\{\begin{array}{1 1}6,(1,6),(2,6),(3,6),(4,6),(5,6),\\(1,1,6),(1,2,6)...........(1,5,6),(2,1,6),\\(2,2,6).......(2,5,6).........(5,1,6),(5,2,6)........\end{array}\right\}$