The class size of 9–12 (Inclusive form) is_______

Answer

To find the class size of the interval 9-12 in inclusive form, we will follow these steps:

### Step-by-Step Solution:

1. **Identify the Class Interval**:
The given class interval is from 9 to 12.

2. **Determine the Lower Limit**:
In inclusive form, we need to adjust the lower limit. We subtract 0.5 from the lower limit:
\[ \text{Lower Limit} = 9 - 0.5 = 8.5 \]

3. **Determine the Upper Limit**:
Similarly, we adjust the upper limit by adding 0.5:
\[ \text{Upper Limit} = 12 + 0.5 = 12.5 \]

4. **Write the Inclusive Class Interval**:
The inclusive class interval is therefore:
\[ 8.5 \text{ to } 12.5 \]

5. **Calculate the Class Size**:
The class size is calculated by subtracting the lower limit from the upper limit:
\[ \text{Class Size} = \text{Upper Limit} - \text{Lower Limit} = 12.5 - 8.5 \]
Performing the calculation:
\[ 12.5 - 8.5 = 4 \]

6. **Final Answer**:
The class size for the interval 9-12 in inclusive form is:
\[ \text{Class Size} = 4 \]