To determine the percentage of the data that is greater than 78, the first step is to identify the value on the number line and the corresponding part on the box plot.
Each division on the number line represents 2 units.
The left side of the box is determined by the first quartile (Q1), if you look at the picture above, the first quartile is equal to 66.
The line in the middle of the box represents the second quartile (Q2) or median of the data set, in this case, the second quartile is 72.
The right side of the box is determined by the third quartile (Q3) of the data set, looking at the number line, the value of the third quartile corresponds to 78.
The third quartile is the value of any data set that divides the bottom 75% of the values from the top 25% of the values.
This means that the percentage of values less than 78 is 75%, and the percentage of values greater than 78 is 25%