From a barrel of colored marbles, you randomly select 3 blue, 8 yellow, 3 red, 6 green, and 4 purple marbles.

Find the theoretical probability of randomly selecting a marble that is NOT yellow.

zero, since it says you selected 8 yellows.

or maybe one, since it lists all the non-yellows you selected.

Now, what you probably meant was that there are 24 marbles, of which 8 are yellow.
P(~yellow) = 16/24