Final answer:
The probability of choosing a marble that is not blue from the bag is 2/3, calculated by dividing the number of non-blue marbles (6) by the total number of marbles (9).
Step-by-step explanation:
To find the probability of choosing a marble that is not blue from a bag containing 5 red marbles, 3 blue marbles, and 1 green marble, we must first determine the total number of marbles that are not blue. When adding the red and green marbles, we get 5 red + 1 green = 6 marbles that are not blue. The total number of marbles in the bag is the sum of all the marbles, which is 5 red + 3 blue + 1 green = 9 marbles.
To calculate the probability, we then divide the number of marbles that are not blue by the total number of marbles, giving us the probability of not drawing a blue marble: P(not blue) = 6/9. This can be simplified to 2/3, which is the probability of choosing a marble that is not blue.