Interpreting Physics Grade Sheet: Percentile, Mean%, & SD Explained

[barcat]

I was wondering if someone could help me interpret a grade sheet I got in physics? Below is a slip that I received after our last quiz.
I understand what the first three columns are, but the Percentile, Mean%, and SD is what is comfusing me. I really do not know where I stand, in this class, compared to the rest of my fellow students.

I tried to copy this to a post, but I would not take. Below is the attatchment.
barry

Quiz Individual Performance GroupPerformance
Max. Score Score(%) Percentile N Mean(%) SD
Quiz 40 36.50 91.25% 42 6 85.63% 11.88
Total 40 36.5 91.3% 42 6 85.6% 11.9

 

[Integral]

Your precential means that you did better the 58% of the people taking the test, N could/should be the number taking the test (6? pretty small class!) SD is the standard deviation, 66% of the scores fall within 1 SD of the mean. For this test 66% of the scores fell between 96% and 84%

 

[barcat]

Integral, thanks for the response. Is there a better way that I
could have posted the bottom part of my request?
I tried to attatch a DOC image, but it would'nt take.

Is 66% a standard for SD? We have 26 students in this class
(internet quizes), I was the first to take it. Also, how did
you arrive at 58%?
barry

 

[Integral]

I read the numbers as

Max. Score Score(%) Percentile N Mean(%) SD
40 36.50 91.25% 42 6 85.63% 11.88
Total 40 36.5 91.3% 42 6 85.6% 11.9

------------Quiz-----Total
Max.------- -40------- 40
Score-------36.5------36.5
Score(%)----91.25%----91.3%
Percentile --42--------42
N-------------6---------6
Mean(%)------85.635----85.6%
SD-----------11.88------11.9

looks like it should read
------------Quiz-----Total
Max.------- -40------- 40
Score-------36.5------36.5
Score(%)----91.25%----91.3%
Percentile --4---------4
N------------26--------26
Mean(%)------85.635----85.6%
SD-----------11.88------11.9

This changes the percentile allot, now you are in the 4th percentile which means you have a better score then 96% of the class


Initially I assumed that the SD was a percent, In reality it may be in points, which seems pretty broad considering it was a 40 point quiz.

1 standard Deviation is defined to be the span around the mean which contains 66% of the things being averaged. You may want to do a web search on the term it is a very commonly used statistic.