Hi Lilia,
For predictive surveys there are many tools that help for that purpose, some of them a little pricy.
Usually the best recommendation tends to be Ekahau, Airmagnet, also Tamograph do the job and is less expensive but with some features missing though.
If the dormitories layout is similar in all of them, it could be very helpful to just take one AP model and to coverage tests in a couple of rooms, that way you can have no predictive but real tests, and the results you have of these tests can be of great help for your design.
Best regards