Four buses carrying 148 students arrive at a football stadium. The buses carry, respectively, 25, 33, 40 and 50 students. After everyone gets off the buses, a random student is picked at random. Let X...

Four buses carrying 148 students arrive at a football stadium. The buses carry, respectively, 25, 33, 40 and 50 students. After everyone gets off the buses, a random student is picked at random. Let X denote the number of students that were on his/her bus. Also, one of the drivers is picked at random. Let Y denote the number of students that were on his/her bus. (a) Compute E[X] and E[Y ]. How do you explain the difference? (b) Compute V ar[X] and V ar[Y ].