It is a combination of passing on two different scales. Firstly you a required to pass 10 out of 14 stations, however you are also required to score equal to or above the overall average mark. It is out of a total mark of 490, so the average for your day may be 320 marks to pass. Therefore you could potentially pass 10 stations, however score below the combined average which means that you would fail. Even if you are struggling in a station try and pick up as many marks as possible with ensuring you do all the basics well.