As the other ladies have said, quota is the number of women who go to pref night divided by the number of sororities. While you all are blessed with 600 women, my school had 58 go through last year....with 8 sororities. Never bitch about voting on pref night
As for your other question James on how many to cut etc, some panhellenics have release figures. These are statistics compiled over a three year period that recommend to each group the number of invitations they give, based on the percentage of past retention. Basically, the release figures require the larger groups to release women sooner from recruitment, allowing those women to explore all options available to them. Without release figures, the largest sororities may invite tons of women back to their parties, with really no intention of extending them a bid.
In terms of quota, you find out what quota is, and then you compile your bid list. The bid list consists of 2 lists. The first list is the list of women you want to give a bid to. It is put in alphabetical order. Your second list is put in preference order, and is used to fill in slots on your first bid list that are vacated when a woman on the first list goes to another sorority. For instance, if quota is 10 and 30 girls come back to your preference party, you list the top 10 you want in alphabetical order on your first bid list. On your second bid list, you list the remaining 20 (or less if there are women you choose not to extend bids to) in preferential order. As the process of bid matching goes through, the bid list is completed with members from the first list, and second if you lost women on your first list to other groups.
Complicated enough??