In order to find the probability of a marble not being blue, we need to find how many marbles are not blue.
To do so, we just need to sum the number of pink, yellow and purple marbles:
[tex]8+4+7=19[/tex]Now, to find the probability, we just need to divide the number of non-blue marbles by the total number of marbles.
[tex]\frac{19}{30}=0.6333=63.33\text{\%}[/tex]