Load the sample data. Create a vector containing the first
column of students' exam grade data.

Crete a normal distribution object by fitting it to the
data.

pd =
NormalDistribution
Normal distribution
mu = 75.0083 [73.4321, 76.5846]
sigma = 8.7202 [7.7391, 9.98843]

Compute the interquartile range of the fitted distribution.

The returned result indicates that the difference between the
75th and 25th percentile of the students' grades is 11.7634.

Use `icdf`

to determine the 75th and
25th percentiles of the students' grades.

Calculate the difference between the 75th and 25th percentiles.
This yields the same result as `iqr`

.

Use `boxplot`

to visualize the interquartile
range.

The top line of the box shows the 75th percentile, and the bottom
line shows the 25th percentile. The center line shows the median,
which is the 50th percentile.