Statistics Guide: A normal population has a mean of 19 and a standard deviation of 5.

In this tutorial, we are going to use excel to calculate a z value from a know mean and standard deviation.

Student Question: A normal population has a mean of 19 and a standard deviation of 5.

To find the z-value at 25, we calculate (25 – mean) / standard deviation =(25-19)/5

Result: 1.20

Finding the proportion between 19 and 25 can be found with the NORMDIST function in excel, then subtracting the result from 0.5.

=(NORMDIST(25,C2,C3, TRUE))-0.5

Result: 0.38493

You can use the same function here, just don’t subtract the result from 0.5.

=NORMDIST(17,C2,C3,TRUE)

Result: 0.34458

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