Finding the probability of each event in a group of events of different possibility.

There are six balls in an urn.  They are identical except for colour. Two are red, three are blue, and one is yellow.  You are to draw a ball from the urn, note its colour, and set it aside. Then you are to draw another ball from the urn and note its colour.
a. Draw a tree diagram to show all possible outcomes of the experiment. Label the possibility associated with each stage of the experiment on the appropriate branch.

b. What is the likelihood that the first ball drawn is red and the second is yellow?

c. What is the likelihood that both balls are of the same colour?