Answer:

Explanation:
Each marble has a probability
of being pulled out of the bag.
We need to pull out green, blue, red or yellow in the first pull.
That is mean we have a
probability to choose one of these. (Let it be green marble)
In secend pull we have 6 marbles in the bag and 3 of them we need to pull out. That is meean we have a probability
to choose one of these (Let it be blue marble).
In third pull we have 5 marbles in the bag and 2 of them we need to pull out. That is meean we have a probability
to choose one of these (Let it be red marble).
In last pull we have 4 marbles in the bag and we need to pull out last one (yellow). That is meean we have a probability
.
