First of all, we arrange the data in ascending order of magnitude;
68, 75, 75, 75, 81, 86, 86, 94, 98.
The minimum value is 68. (That is, the smallest value)
The maximum value is 98 (That is, the highest value)
The median value is the number at the middle.
Median = 81
The lower quartile (first quartile) is denoted as Q1;
lower quartile is the central point between the smallest value and the median.
Hence, lower quartile = 75
The upper quartile denoted as Q3;
Upper quartile is the central point between the median and the highest value.
Hence, upper quartile = 86