Is it possbile to score in the 100th percentile on a given standardized test?I would think no but why not?

2 answers

No. The highest percentile is the 99th percentile.

http://www.regentsprep.org/Regents/math/ALGEBRA/AD6/quartiles.htm

"To put it in words, being in the 100 percentile would mean that 100% of the group has marks below yours. But since 100% of the group would include you, and your mark could never be below your mark, then 100% of the group could not be below you. Therefore you could never be in the 100 percentile."
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http://math.stackexchange.com/questions/33488/how-to-calculate-percentile-is-it-possible-to-get-100-percentile
No. The highest percentile is the 99th percentile. (This is the correct answer for Ashford University)