Need help answering this question:

If a student scores a 54% and is in the 90th percentile, how well did the class do?

Need help answering this question:

If a student scores a 54% and is in the 90th percentile, how well did the class do?

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Miami, FL

If the score is 54% and is in the 90% of the class it means that the average of the class was near the student's grade so the distribution of the grades is near 60%. Then, the class did not do well.

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## Comments

If I'm in the 90th percentile, it means that my score was better than 90% of the class. (That's the part that seems to trip up students.) If I'm in the 99th percentile, it means that I was basically better than everyone. If I'm in the 25th percentile, it means that I was only better than 25% of the class, so 75% of the class out-scored me.

In this problem, the student in question got a 54%, which sounds pretty awful, and they were in the 90th percentile. So, what does that mean? 90% of the class did worse than a 54%. Only 10% of the class got better than a 54%.

How does that mean that the average of the class was near the student's grade? The average could have been like a 30%, or a 40%, or maybe a 50% if lots of people were bunched there...but none of those gets "a distribution of the grades near 60%," and it doesn't mean that the average was near the student's grade necessarily.

What am I not getting?

-- Michael