Submission fail

i got all my test cases pass but in submission i got fail grade

Are there any Comments on Submission ??

The test cases present in your notebook are public test cases which means everyone including you can see them, but while you submit a notebook the notebook is checked upon some private test cases, which is not visible to us.
I guess there is a little problem with your code, check this part are you comparing the mid_number with the number present in the highest index of the list or are you just comparing the middle number with the highest index of the list. (I mentioned this as this is a common error, this may not be the same for you).

yes test case 4 and 5 fail