Pablo randomly picks three marbles from a bag of eight marbles (four red ones, two green ones, and two yellow ones). how many outcomes are there in the sample space?

The answer is 336.

Sol'n:

8P3 = 336 ways
where P = permutation

We use Permutation rather than Combination.
In the problem, it asks for the outcome or ways. Pablo picked 3 marbles over the eight marbles but it didn't mention if he picked a yellow, green, or red marble. In this state, you are going to assume that he picked random color of marbles. In that case, you are going to use Permutation. 

The correct answer is addition