<p>^Since 21.1 is the mean (equivalent to SAT 1500) and she scored 21.5, that puts her between normal and 1SD at age 13. That would be the interval between 1500 and 1800 on the SAT. So, no slouch to begin with, better than the average high school senior at age 13. :)</p>
<p>To score above 32 she had to move across two standard deviations in 4 years. Most kids improve about one SD after age 13. So, she continued to improve faster than most kids in high school. It is possible to improve this fast but not too much faster than this, after age 13, which is why I said, </p>
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