How are multi-select Part A/Part B questions scored?

Imagine a 5-question assignment with one Part A multi-select question and one Part B multi-select question. These questions are related (in other words, a student’s success on Part B depends upon his or her success on Part A).

Let’s say a student correctly answers all 3 of the other questions on the assignment. Here is how the scoring works:

• If Part A has TWO correct answers, the student will receive full credit for Part A; If Part B has TWO correct answers, the student will receive full credit for Part B. The score for this assignment would be a 5/5 (100%).
• If Part A has TWO correct answers, the student will receive full credit for Part A; If Part B has only ONE correct answer, the student will receive half credit for Part B. The score for this assignment would be a 4.5/5 (90%).
• If Part A has TWO correct answers, the student will receive full credit for Part A; If Part B has NO correct answers, the student will receive zero credit for Part B. The score for this assignment would be a 4/5 (80%).
• If Part A has ONE correct answer, the student will receive half credit for Part A; If Part B has TWO correct answers, the student will receive full credit for Part B. The score for this assignment would be a 4.5/5 (90%).
• If Part A has ONE correct answer, the student will receive half credit for Part A;  If Part B has ONE correct answer, the student will receive half credit for Part B. The score for this assignment would be a 4/5 (80%).
• If Part A has ONE correct answer, the student will receive half credit for Part A;  If Part B has NO correct answers, the student will receive zero credit for Part B. The score for this assignment would be a 3.5/5 (70%).  
• If Part A has NO correct answers, the student will receive zero credit for Part A, and Part B will be completely omitted from all data calculations regardless of whether or not the student chose any correct answers. That means that Part B will not count towards the student’s score at all (it cannot hurt nor help them). This is because Part B’s correctness is dependent upon Part A being correct. In this case, the score for this assignment would be a 3/4 (75%).