Geometry

Question Analysis
This question involves the basic concept of probability within the context of a simple object - selection scenario.
The main focus is on applying the probability formula for a discrete event.

Key Concept Explanation
Probability of an event is calculated as the number of favorable outcomes divided by the total number of possible outcomes.
In this case, the favorable outcome is selecting a blue marble, and the total possible outcomes are all the marbles in the bag.

Step - by - Step Solution
First, find the total number of marbles in the bag.
Add the number of red, blue, and green marbles: marbles.
The number of favorable outcomes (selecting a blue marble) is 3.
Using the probability formula

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