Ah, Yeah I got that. Also went for the midpoint for the mean, But I thought that was the sample mean while it wanted the population mean so I was confused, Think it's right though.
As always I couldn't think of reasons why It's not a poisson distribution, I pretty much take off two marks on every paper knowing I'll get that one wrong. What was the answer?
Poisson has no upper limit (book stores said you can have a maximum of 6 books) and borrowing books doesn't occur at a constant average rate (library closes/opens at certain dates/times)
I had no idea what to put as to the second mark for the DRV/Poisson bit (For the first I said variance does not equal mean) so I put the events do not occur randomly or singly, anyone think this will get me a mark?