I have a question relating to Poisson which I would like to get some advice on. I am doing this on a self-help exercise, but unfortunately it doesn't provide answers for me to verify.

Basically in the question, it provides me with the premise that a server in a datacenter will under-go an unplanned system reboot every 40 days. 

So, to find the probability that the time between TWO unplanned server reboots is less than 4 weeks, I use the expression $P( 2x < 28)$, where $2x$ is because of 2 unplanned server reboots and 28 because 4 weeks is equals to 28 days. I was wondering if I am on the right track on this?