First, don't be discourage. The quizzes can be difficult which is why we recommend taking the quiz more than once and moving on once you have three out of five correct. The difficult thing about the questions is they often test multiple concepts within one question, unlike the lesson videos which are focused on very targeted concepts. Our quizzes are taken from our question pool of GMAT level question so it may pool a question that uses a math concept from the lesson videos as well as a math concept from a video you have not gone over yet.
Try to think of the quizzes as an extension of the lesson. Don't worry about passing it right away, but try to learn from the questions. When you finish the quiz watch each of the explanation videos and corresponding lesson videos. As you review the question ask yourself the following questions:
- Why you missed the question?
- Why your answer is wrong?
- Why the correct answer is correct?
- What will you do to avoid this next time around?
Then, retake the quiz.
If you are still having trouble with the quiz, try setting up a custom practice for the topic you are working on. Start by setting the difficulty level to easy and then work your way up to harder questions. Once you feel comfortable with the topic, move on to the next topic.