To find the total number of students at McCord Middle School, you can use the information provided:
- The number of students who rode their bike or walked to school is 300.
- This represents 60% of the total student body.
Let \( x \) be the total number of students at the school.
From the problem, we can set up the equation:
\[ 0.60x = 300 \]
To solve for \( x \), divide both sides by 0.60:
\[ x = \frac{300}{0.60} \]
Calculating that gives:
\[ x = 500 \]
Thus, the total number of students attending McCord Middle School is 500 students.
The correct answer is 500 students.