The manager of an express oil change service has determined that the number

The manager of an express oil change service has determined that the number of customer who arrive in a one hour time interval (x) can be modeled using a Poisson model with mean =2.5 customer per.
what is the standard deviation of the number of customers that arrive within a 2hour time interval

The manager of an express oil change service has determined that the number of customer who arrive in a one hour time interval (x) can be modeled using a poisson model with mean =2.5 customer per.
if the number of customers who arrive over a 2 hour interval is 2 or fewer, the manager will close down one of the service bays & send the crew home. what is the probability that a 2 hour time interval will have 2 or fewer customer arriving for service

The manager of an express oil change service has determined that the number of customer who arrive in a one hour time interval (x) can be modeled using a poisson model with mean =2.5 customer per hour.
If currently the service is open until 9pm for the coming Friday night, the manager has decided that i or fewer customer arrive in each of the 3 one hour time interval 6-7:00, 7-8:00 & 8-9:00pm, he will change the closing time to 6pm what is the probaility that there will be i or fewer customers arriving each of the 3 one-hour time interval this friday night? ( recall the number of arrival in any one-hour is independent of the number of arrival in any other one-hour interval)