How to prove that average complexity is N/2 for linear search in the unsorted array [duplicate]

Question

This question already has an answer here:

• Why does linear search have $\frac{n}{2}$ comparisons on average? 2 answers

All tutorials on algorithms show the complexity for the linear search in the unsorted array in the average case as N/2. I understand that the average case means the items in the list are randomly distributed.

Can anyone show how I would arrive at N/2 if I have items randomly distributed? Or does it come out of randomly shuffling array bazillion times and recording the number of operations?