Drupal development

General information for the business: consulting firm
Kind of development: Customization of existing program

Description of requirements/functionality: We have a Drupal 7 web site with 10 fivestar fields in a node content.
Those fivestar fields range from 0 to 4 stars.
=> the goal is to develop an additional field that will perform an average of the 10 fivestars fields value.

This average should be saved in database so we can use it later in a view in order to rank / filter this view by that average.

**NOTE: **
As the web site is private for a customer and that we've signed confidentiality agreeement, we'd like to find a solution where you do not need an access to the website nor by FTP.
We'd like a solutiion where you replicate the 10 fivestar fields with the exact name on a dummy site of yours and work from that dummy site.


Specific technologies required: DRUPAL, php
Extra notes: Attached are pcitures of the fivestar nodes field