http://www.ck12.org Chapter 5. Normal Distribution
If we had to estimate an actual value first, we know from the empirical rule that about 84% of the data is below one
standard deviation to the right of the mean.
μ+ 1 σ= 35 + 7. 4 = 42. 4We expect the answer to be slightly below this value.
When we were given a value of the variable and were asked to find the percentage or probability, we used thez−table
or anormalcdfcommand. But how do we find a value given the percentage? Again, the table has its limitations in
this case and graphing calculators or computer software are much more convenient and accurate. The command on
the TI-83/84 calculator isinvNorm.You may have seen it already in the distribution menu.
The syntax for this command is:
InvNorm (percentage or probability to the left, mean, standard deviation)
Enter the values in the correct order: