Hints

1. Non-Passing Students

Try using one of the loops that is iteration centric.

2. Get the average grade of students

Try using one of the loops that is condition centric using numberOfStudents as one of the core conditions.

3. Calculating letter grades

Remember that there is a condition centric loop that guarantees the body to be executed at least once.

4. Matching Names to Scores

Try using a iteration centric loop that allow you to work with indexes.

5. Count Odd Scores

Remember that you could use the modulus operator % to check if a division has a certain reminder.
Try using a iteration centric loop
Check the statements/keywords covered in the concept an use one of them.

6. Challenging Exam

Try using a iteration centric loop
Check the statements/keywords covered in the concept an use one of them.