@tc2002 It depends. Over the last couple of years the relative difficulty of the test and the scaling (relationship of # of mistakes to composite score) has varied a lot. So 5 mistakes on one test might be a 1550 and on another test could be a 1490. You should focus on the number of mistakes you make as well as your score to see if you are improving.
For both of my kids, their real scores were consistent with the range they saw on practice tests.