<p>I took AP STAT last year and got a 5 on the test. I am fairly aware of stat terms and statistics in general. However, when you say a 25th percentile is 1320 and the 75th percentile is around 1500. Therefore, the 50th percentile, which is roughly close to the mean should be a 1410. The range you sited is last year’s published range for Northwestern’s freshman class. Therefore, if last year’s average was a 1398, then the published range for last year is indeed inaccurate.</p>