Answer:
I studied hard for my midterm exam; I should be confident in my answers.
Step-by-step explanation:
The given statement can be divided into 2
1: I studied hard for my midterm exam
2: I should be confident in my answers
(1) & (2) are both independent clauses and when independent clauses meet to form a bigger sentence, the right punctuation to use is a semicolon.
Hence:
The complete sentence is
I studied hard for my midterm exam; I should be confident in my answers.