Answer:
1 / 3
Explanation:
Probability can be represented as the amount of desirable outcomes divided by the total number of outcomes.
Because there are 8 + 5 + 2 marbles or 15, it would the total number of outcomes.
The desirable outcomes can be represented as blue marbles, which there are 5 of.
Using this and the formula above, the probability for picking a blue marble is 5 / 15 which simplifies to 1 / 3.