A fast food service kiosk employs 1 one cashierat its counter. 40 customers arrive on average every 25 monites. Thecashier can serve 20 customers every 10 minutes. Assuming poison distribution for arrival and exponential distribution for services rate. Find;

a) average number of customers in queue

b) average time a customer spends in a system

c) average time a customer waits before being served

d) average number of customers in the system