. Consider the following possible routes (the lines in the figure) for a person to start from point
A to reach point B. The only condition imposed on the journey is that the person can only go
east or north.

(a) Suppose that all the possible routes can be chosen with equal chance. What is the prob-
ability that the person will pass through point C?
(b) Suppose that wherever the person has a choice, he chooses to go east or north with equal
chance. What is the probability that the person will pass through point C?