Normally, you can do the next question you must pass the current question. So you can complete one section you must correct all questions in the section.
75% Pass Mark has process from user attempts to answer the question. Because in this course you will never got failed question. You had to try-again to answer the question until you got the correct answer then you can go to do the next question.
75%% Pass Mark is the percentage that you must passed in all questions. Then 25% is the percentage that you can attempt to fail the question.
So, currently the course has 27 questions. It is mean when you had attempt to answer the question and you got incorrect answer 7 times (25% of 27 is 7). You failed the course.