3 3-hour exams in a row with no time in between. What can I do? I am currently studying computer science in a University in Canada.

I have just received my Schedule for the semester, and I have noticed that, during the finals week, 3 of my 6 courses put their final exams in the same day.

Specifically, I have an exam from 12:30 to 15:20, another one from 15:30 to 18:20 and the last one is from 18:30 to 21:20. All three of those exams are Worth 35% or more of my grade, therefore are very likely to be decisive in my success or failure this semester.

This really seems unreasonable to me. I do not expect, no matter how much sleep I get and how much coffee I drink, to be able to perform at my best for 9 hours straight, without even a chance to eat dinner.

So I have two questions:
First, is this standard practice? I'm only starting my second semester, so maybe I just got Lucky the first time that all my exams were the only one of the day.

And Second, if this is not standard but rather a very unlucky setup, do I have any recourse? Is it rude to ask some of the professors or higher-ups in the school to change the Schedule a little?

It is also important to know that I am taking the classes in the standard path (? I am not a native English speaker, but I am referring to the grid thing telling me the recommended courses to take every semester in order to complete the program in the fewest number of semesters) for my program. I am not taking any special classes that are not expected to be taken at the same time. This means that a lot of people probably have this exact Schedule for this semester, and it's not just me because I made weird choices.

EDIT: Thank you all for your input. I will accept one of the answers now, but to be honest, they were all pretty enlightening. I had already sent an email to all concerned professors AND the faculty 5 days prior to asking this question, and I still haven't received an answer. I will probably forward the same email (it is as polite as possible, asking about what are my options in the context, etc) to some more administration adresses in the hopes that someone can give me the exact policy, or at least tell me who can.

I am very glad that everyone seems to agree that they can usually do something about it, this makes me less stressed. In the worst case, nothing changes, and as one answer mentioned, if lots of students have a worse grade because of this setup, then the playing field is even.
Whether this is a standard practice or not highly depends on your university. However, the attribution of these exam period is an automated process and some situations like yours are bound to happen. 

If I were you, I would consult the specific rules of your University. I know at that my previous Canadian University in Montreal (École Polytechnique), there was a rule that limited the amount of exam hours you could have in a 24 hours period, ( I believe it was 6 maximum per day). If such a thing occurred, you could ask for the exam to be moved as this was judged to be unfair.

You can also consult with your student committee (of your department or your faculty) and your department since you say that you are following a standard path. In that case, there will be many students in the same situation and they should prove to be understanding. The student committee can usually present a uniform front and defend the entire class as a whole concerning this issue. There is absolutely nothing impolite about this if you proceed politely and you act as soon as the semester begins. The sooner you handle this issue, the easier it will be to solve.

I believe you are right in saying that this will not allow you to perform to your full potential, and you are right to ask for a more humane schedule.