1. The user requested two separate practice exams with answer keys covering four sections based on the Ontario Grade 8 curriculum: data management, algebra, geometry, and perimeter/area/volume. 2. Since the request is for multiple sections and multiple questions, I will only solve the first question of the first section as per the guest rule. 3. First question in data management: Calculate the mean of the data set: 4, 8, 6, 5, 3. 4. The formula for mean is $$\text{Mean} = \frac{\text{Sum of all data values}}{\text{Number of data values}}$$. 5. Sum the data values: $$4 + 8 + 6 + 5 + 3 = 26$$. 6. Count the number of data values: 5. 7. Calculate the mean: $$\frac{26}{5} = 5.2$$. 8. Therefore, the mean of the data set is 5.2.