First time renting to "real" tenant

[Vy Mai]

Ever since we purchased our first rental property, our seller has been renting back from us.  They will move out in August and we have been advertising for new tenants.  So this group of 4 students are interested. The rooms are different in sizes so I imagine they would want to be charged differently. Do I let them decide on how much should each of them pay? Or should I name the price tag on each room?  Thanks for answering!