You want to estimate the average unit process time (a.k.a. activity time), p, at a server. You are told that there are four identical parallel resources (m = 3), the server works for 8 hours or 480 minutes each day, the average utilization at this server is 0.7 (or 70%), and the customer arrival rate is 80 units / day.
Among the options below pick the one that most correctly estimates the average unit activity time, p, corresponding to the above data. Please show formulas, and thank you for your assistance!!
a. Less than 3 minutes
b. At least 3 minutes but less than 6 minutes
c. At least 6 minutes but less than 9 minutes
d. At least 9 minutes but less than 12 minutes
e. At least 12 minutes but less than 15 minutes
f. At least 15 minutes
g. Cannot say