Radius weight and priority

Hi

I'm looking at a detailed doumnetation on priority and weight,I found this on ms press 

Using priority and weight settings for the group members in a remote RADIUS server group

enables you to do load balancing for the group. Within a group, the primary server has a priority of 1.

All members of the group with the same priority are sent RADIUS messages in weighted order.

Consider server group RADIUS1, with three members (server1, server2, and server3) in the group.

All servers have a priority of 1, and the servers have the following weights:

Server1, weight 10

Server2, weight 15

Server3, weight 25

If the RADIUS proxy has 100 RADIUS messages for the group to process, server1 will be sent 20

to process, server2 will get 30 messages, and server3 will process 50 messages.

But how is it calculated?

and if i have two servers with priority 5 and weight 50

and one server with priority 90 and weight 70, how does it exactly work? i read somewhere that the servers with lover priority are used until they are not avaialble, is that thru?

thank you