To determine the probability that Jenna will pull a yellow marble from the bag, we need to know the total number of marbles as well as the number of yellow marbles in the bag. The probability \( P \) of drawing a yellow marble can be calculated using the formula:
\[ P(\text{yellow}) = \frac{\text{Number of yellow marbles}}{\text{Total number of marbles}} \]
Once you provide the specific counts of blue, red, and yellow marbles, we can compute the probability.