Four buses carrying 154 high school students arrive to Montreal. The buses carry, respectively, 31, 45, 34, and 44 students. One of the studetns is randomly selected. Let X denote the number of students that were on the bus carrying this randomly selected student. One of the 4 bus drivers is also randomly selected. Let Y denote the number of students on his bus. Compute the expectations and variances of X and Y?