Samuel is an encyclopedia salesman. In order to make his life more interesting, when he encounters an intersection of two streets, he heads east 30% of the time and north the other 70%. He will walk 50 blocks (intersection-to-intersection) each day. West-East blocks contain 4 houses each and North-South blocks contain 6.
a. On a certain day, how many houses does he expect to visit?
b. Find an expression for the probability that he visits 290 or more houses. You do not need to simplify or evaluate the expression.