Likert Scale - Not Applicable Option

I have the following scales:

1 (Strongly Disagree);
2 (Disagree);
3 (Not Applicable);
4 (Agree);
5 (Strongly Agree);
Questionnaire responses:

Question Item1: 2;
Question Item2: 3;
Question Item3: 1;
Question Item4: 1;
Question Item5: 4;

If I need to average the above responses into the Excel Sheet, while treating Question Item2: as null (since it is being excluded from the equation), Which of the formula (attached) is more appropriate to adopt and why?

Kindly advise.


TS Contributor
I think neither. The problem is that Not Applicable does not measure what the other scale items measure (namely feelings) so you do not have roughly equal distances between the scale elements, so strictly, you can not treat this scale as an interval variable, so no averaging is, strictly seen, valid. It should have been something like "I do not care" instead of NA to make it a correct Likert scale.