Answer as many questions as you can to the best of your ability. And, read each question and answer thoroughly before answering.
Don't try and keep score; don't worry about the question you previously answered and don't worry about which of the questions are unscored. All of these are a waste of brain-power that is better focused on the question in front of you at the moment.
Also, it is not 70%. You need to earn 700 points out of a possible 1000. That is not the same thing because some questions are worth more points than others. Since you have insufficient information to do the math, don't distract yourself by guessing about how well you are doing.
Just do your best to pick the answer you feel best on each question. And, remember, there can be more than one "correct" answer. Your job is to pick the best answer amongst them.
