# Statistics

On a chemistry exam, Student A scored a 81 and Student B scored a 70. The mean for the class was 75 and the standard deviation was 3.8.
What percentage of students scored in somewhere in between Student A and Student B?

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1. about 15 percent if you believe it was a normal distribution. Seldom it is.

http://davidmlane.com/hyperstat/z_table.html

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2. Here is another method.

If it approximates a normal distribution, you can use

Z = (score-mean)/SD

Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to the Z scores.

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posted by PsyDAG

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