Each student in a classroom has chosen either a green, red, or blue marble and written their initials on it. in addition,
some of the marbles have the letter a written on them, and some of the marbles have the letter b written on them. all of
the marbles are shown below.
red marbles
green marbles
blue marbles
all of the marbles are placed in a bag, and then one is randomly selected.
a. the probability that the selected marble will have a b written on it is