If 276 is the magic number then it probably means you are in a state where the MBE counts for 50% of total score. That means you need to average a 138 on the two sections to pass. You could go below 138 on one section say 133 and get 144 on the other and pass with a whole 1 pt to spare but you have to average 138. The people who did the MBE will scale the score for the bar, its scaled on a national level. That can be good or bad, the larger the population of the field the data is coming from the less difference there will be year to year in average scores so if you have a smarter than normal class in a state one year it won't hurt them.
Most states also scale their essays part using the MBE. For example they take raw essay score, standard deviation of essay score, the states testakers average MBE score, and standard deviation and multiple them. Else standardizing the essay scores would be too hard. Roughly this means that the MBE scores and Essay scores are lined up for example the 110 out 1000 MBE score might be 160 and the 110 out 1000 essay score in the state woud also be around 160 and right down the line. Therefore the scaling of the MBE score is not only important for the MBE it pretty much determines the essay scales in most states.