Joe, I believe that the chart indicates 247 is 95th percentile for Spring Reading NWEA for an 8th grader, and 290 is off the chart for anybody. 99th percentile for 8th grade Spring Math is 279. If you were in 11th grade, 99th percentile would be 286.
ABC, Winter Math 4th grade, 224 is 87-88th percentile, which is probably well ahead of the curve for her class.
Assuming I'm reading the chart correctly, of course. Those do sound like correct percentiles, from my experience with NWEA scores.
The scores do generally come on a chart from the school (at least ours do) that shows class or group averages along with your child's score, in lines of progression so you can see where you are compared to the rest, and how much progress is being made through the year. It also lists the average ranges for each set of individual skills within a test.