1. **Problem:** Work out the mean, median and mode for the data: 5, 9, 12, 4, 5, 14, 19, 16, 3, 5, 7. 2. **Mean formula:** $$\text{Mean} = \frac{\text{Sum of all data values}}{\text{Number of data values}}$$ 3. **Median:** The middle value when data is ordered. 4. **Mode:** The most frequent value. 5. **Step 1:** Order the data: 3, 4, 5, 5, 5, 7, 9, 12, 14, 16, 19. 6. **Step 2:** Calculate mean: $$\text{Sum} = 3 + 4 + 5 + 5 + 5 + 7 + 9 + 12 + 14 + 16 + 19 = 99$$ Number of values = 11 $$\text{Mean} = \frac{99}{11} = 9$$ 7. **Step 3:** Find median: Number of values is odd (11), median is the 6th value. 6th value in ordered list is 7. 8. **Step 4:** Find mode: Value 5 appears 3 times, more than any other. Mode = 5. **Final answers:** Mean = 9, Median = 7, Mode = 5.