Four buses carrying 155 high school students arrive to Montreal. The buses carry, respectively, 40, 42, 25, and 48 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: