*This is a real world scenario - please help. My brain hurts and I can't figure it out on my own.*

Suppose I host an event with the following constraints

* **There will be exactly 5 lectures**
* **There will be exactly 125 participants**
* **Each participant has signed up for exactly 3 mandatory, unique lectures** (so each lecture has exactly 75 participants)
* **There are exactly 5 rooms available, each room holds 25 people** (so each lecture has to be held at least 3 times)

Assuming a lecture will last one hour (including pauses), will I be able to finish the event in 3 hours? How do I calculate this?

*Thanks for your help...I need it :-)*