To find the range of the quiz scores from a box-and-whisker plot, you need to use the maximum and minimum values of the data set.
The range is calculated using the formula:
\[ \text{Range} = \text{Maximum} - \text{Minimum} \]
From the values you've provided, it seems the minimum score is 15 and the maximum score is 33.
Using these values:
\[ \text{Range} = 33 - 15 = 18 \]
Therefore, the range of the quiz scores is 18 points.