One die of red colour,one of white colour and one of blue colour are placed in a bag. One die is selected at random and rolled,its colour and the number on its uppermost face is noted. Describe the sample space.

$A$ die has six faces that are numbered from $1$ to $6,$ with one number on each face. Let us denote the red,white,and blue dice as $R$,$W$,and $B$ respectively.
Accordingly,when a die is selected and then rolled,the sample space $S$ is given by the set of all possible outcomes of the form (colour,number):
$S = \{R1, R2, R3, R4, R5, R6, W1, W2, W3, W4, W5, W6, B1, B2, B3, B4, B5, B6\}$