From the model Ⅰ we can see: s1 c refers to the cost of handling service which is provided by handling facilities
in unit time, whenμ =1. μ s1 c refers to the cost of handling service which is provided by the single desk in the unit
time. However, in model Ⅱ, s2 c refers to the cost of handling service which is provided by every service desk in the
unit time. Therefore, the meaning of μ s1 c in model Ⅰ is equivalent to the meaning of s2 c model two. From this we
can see, in the case of other conditions are same, s1 s2 c μ = c . Supposing s s1 c = c , then c s c s c s s s s= μ = μ 2 1 .