The range of the rainfall data set is 20 mm.
To find the range of a data set represented in a stem-and-leaf plot, you need to identify the smallest and largest values.
The smallest value is 49 (stem 8, leaf 4), and the largest value is 69 (stem 15, leaf 9).
Range = Largest Value - Smallest Value
Range = 69 - 49 = 20
So, the range of the rainfall data set is 20 mm.