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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 -

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

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

  • Statistics -

    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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