To determine if a data set has a mode, we need to identify the value or values that appear most frequently. In this case, the data set 3, 3, 3, 4, 4, 4, 5, 5, 5 has three distinct values: 3, 4, and 5. Each value appears three times, which means all the values have the same frequency. Therefore, this data set has multiple modes, specifically 3, 4, and 5.
