Your isEven() method does not even slightly fulfill your requirements. I don't think it will compile. Ditto isOdd().
Please don't anybody give any more hints, otherwise you will overstep the line between helping and
doing somebody else's assignment.
You are not going about things correctly.
You should not be creating a whole class. You should create a little class with an isEven method only, execute and
test that, then add an isOdd method, and so on. You will find it much easier if you develop in tiny bits.
Draw your UML diagrams first. They can easily be drawn from the specification you are given and you can pick up 10% of your marks in 20 minutes.