Each magazine that Charlie reads takes an amount of time that follows an exponential distribution with mean 10 minutes. The number of magazines that Charlie reads on any given day has a Poisson distribution with mean 2 . Assume that each reading session always falls within a single day (he does not read past midnight).

Question

Furthermore, suppose that the number of magazines that Charlie reads on different days are independent, and that the lengths of time he takes to read each magazine is also independent of each other.

For simplicity, assume that he only reads 1 magazine at a time and that there are 30 days in each given month.

Let T be the total number of minutes Charlie spends reading magazines in one month.

E(T) =
VAR(T) =

Answer 1

600
12000

part b?

Answer 2

1) 600
2) 12000
3) 0 (not sure)

Answer 3

about 3: Sn ~ N(720, 720), 99.73% of the realizations lie between 639 and 800 magazines/year -> P(3500 < Z < 3600) = 0

Answer 4

Part 3
is 0 the final answer

Answer 5

Why part 2 is 12,000 and not 17,400 (12,000 + 5,400)?