Question

Four buses carrying 160 students from the same school arrive at a football stadium. The buses carry, respectively, 42, 36, 34, and 48 students. One of the students is randomly selected. Let X denote the number of students that were on the bus carrying the randomly selected student. One of the 4 bus drivers is also randomly selected. Let Y denote the number of students on that bus. Then E[X] and E[Y] respectively are 

(a) 50, 40

(b) 40, 50 

(c) 40.75, 40 

(d) 41,41

Answer 1

(c) 40.75, 40

E[X] > E[Y], Since the students selected is more likely to come from the bus carrying maximum number of students whereas the drivers are equally likely to be selected.