$($b$)$ At general stores, customer arrive according to Poisson distribution with mean arrival rate of $5$ per hour and the service time in exponential distribution with an average service time of $10$ minutes. It is assumed that because of excellent reputation of store, customers are willing to wait. Calculate the following :

$($i$)$ Average number of customers in the shop and the average numbers waiting for a service.

$($ii$)$ The percentage of time arrival can walk in straight without having to wait.

$($iii$)$ The percentage of customers who have to wait before getting the service.