To answer this question, we will use the following expression to find the probability:
[tex]\frac{\text{favorable outcomes}}{total\text{ outcomes}}.[/tex]Since there are 3 red marbles, the number of favorable cases is 3. The total number of marbles is
[tex]3+6+2+8=19,[/tex]therefore, the total number of outcomes is 19.
Substituting the above values in the expression, we get:
[tex]\frac{3}{19}\text{.}[/tex]Answer:
[tex]\frac{3}{19}\text{.}[/tex]