The range is 10.
Range is the difference between the smallest and largest values. In this data set, 4 is the minimum number of hours and 14 is the maximum number of hours someone spent studying. 14 - 4 = 10 hours.
Here is the data in order from least to greatest: 4, 4.5, 5, 6, 6.5, 8, 9, 9.5, 14