Posted by **robyn** on Sunday, February 12, 2012 at 4:50pm.

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?

- Statistics -
**bobpursley**, Sunday, February 12, 2012 at 6:07pm
about 15 percent if you believe it was a normal distribution. Seldom it is.

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

- Statistics -
**PsyDAG**, Monday, February 13, 2012 at 1:56pm
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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