The mark of the class `90-120` is

Options

A. 90
B. 105
C. 115
D. 120

Explanation

To find the class mark for the class interval `90-120`, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Lower and Upper Limits**:
- The lower limit of the class is 90.
- The upper limit of the class is 120.

2. **Use the Formula for Class Mark**:
- The formula for calculating the class mark (also known as the midpoint) is:
\[ \text{Class Mark} = \frac{\text{Lower Limit} + \text{Upper Limit}}{2} \]

3. **Substitute the Values into the Formula**:
- Substitute the lower limit (90) and the upper limit (120) into the formula:
\[ \text{Class Mark} = \frac{90 + 120}{2} \]

4. **Calculate the Sum**:
- First, calculate the sum of the lower and upper limits:
\[ 90 + 120 = 210 \]

5. **Divide by 2**:
- Now, divide the sum by 2 to find the class mark:
\[ \text{Class Mark} = \frac{210}{2} = 105 \]

6. **Conclusion**:
- Therefore, the class mark for the class interval `90-120` is **105**.