Previous exams with solutions may be available one week before each exam.

Note that, except for the fact that these exams cover a similar range of materials you should not expect your exam to be itself similar to an old exam. Thus, you should never study from the previous exams.
Instead, you should solve previous exams just to evaluate yourself. If you do a problem incorrectly, try to review the concept then do the problem again on your own and do other problems from the text to reinforce the concept(s).
Also keep in mind that not all the concepts covered in lecture appear on each exam. You should base your study on what was covered in lecture.