Answer:
3 ; 1 minute ;75%
Step-by-step explanation:
Given :
Service time = 15 seconds = 15/60 = 0.25 minute per customer
μ = number of customers per minute = 1/0.25 = 4
Arrival rate, λ= 3 persons per minute
L = λ ÷ (μ - λ)
L = 3 ÷ (4 - 3)
L = 3 ÷ 1
L = 3
b) How long would you expect it to take to get a cup of coffee?
L / arrival rate (λ)
3 / 3
= 1 minute
c) What percentage of time is the urn being used?
Utilization rate = λ/ μ
= 3 / 4
= 0.75 = 0.75 * 100% = 75%