Hi, this question is about queuing theory, I hope you'd be able to help. I've been struggling for days and still haven't figured it out.

Suppose there are two types of elevators. Buildings A and B have the same number of floors.

Assume that passengers take the elevator at the lobby, and only go up.

There is no inter-floor traffic, and once the elevator unloads all passengers, it will come back to the lobby, empty, and without distraction.

Building A has 2 elevators that serve all floors.

Building B has 2 elevators that serve only half of the floors. One elevator serves only the bottom half (may be 1-5) and the other elevator serves the upper half (may be 6-10).

a) How do the average queuing time differ between the two buildings?

b) How do the average # of passengers queuing differ?

c) How do the average amount of time in system differ?

d) How do the average # of passengers in system differ?

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What I think about the above question is that it's a difference between One M/M/2 system and Two M/M/1 systems. Please correct me if I'm wrong.

The point that I'm confused is, I think would be different because Building B elevators only serve half of the floors, but how do I model that?

I'm really poor at math, so detailed explanations would be really helpful!

I'm a 1st year masters student in business.

Thanks a lot!