Four buses carrying 141 high school students arrives in Montreal. The buses carry, respectively, 32, 44, 26, and 39 students. One of the students 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 variances of X and Y:

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vishal_kothari · Answer

it will help http://answers.yahoo.com/question/index?qid=20090329154430AAhCZSE

anonymous · Answer

@vishal kothari Thanks, It annoys that I don't know head and tail about it, feel like I'm reading Chinese language :(

anonymous · Answer

sorry，that ia want to know the variance not the expectation,anyway thanks