Estimate the average time-length that a student is enrolled at the university (including students who graduate and those transfer or drop out)
My thought: I computed the percentage of new student, classified as either first-year or transfer, in each of year 1-5. I also computed the number of students who dropped out in each year (but I could not determine how long they stay, which is the key point). Anyway, I think we could use Little's Law ($L_i = \lambda_i W_i$), but I am stuck on getting $\lambda$ and $W$ (is $W_i$ equal to the total enrollment in year i? Similarly, is $\lambda_i$ equal to the total number of new students in year i?).
My question: I would sincerely appreciate if someone could give some thought on this problem.
I think you are correct that this is supposed to be an exercise using and understanding Little's Law.
Average 'Enrollment', which I would view as $L$ (number in system) seems fairly stable around 17,000. So it seems realistic to assume the system is at steady state. (You can find the mean, instead of my rough guess of 17,000.)
I would view 'New Students' as providing information on $\lambda$ (rate of entry).
From $L$ and $\lambda,$ I guess you are supposed to estimate $W$ (average time in system).
If $W$ is to be average years in the system, then you have to express $\lambda$ as rate of entry per year.