To find the average number of students in the class who said they would benefit from tutoring, we can use the information provided about the confidence interval.
Given:
- Lower margin: 13
- Upper margin: 21
- Margin of error: ±4
The average (point estimate) of the number of students can be calculated as the midpoint of the lower and upper margins. This can be done using the formula for the midpoint:
\[ \text{Average} = \frac{\text{Lower margin} + \text{Upper margin}}{2} \]
Substituting in the values:
\[ \text{Average} = \frac{13 + 21}{2} = \frac{34}{2} = 17 \]
Therefore, the average number of students in the class who said they would benefit from tutoring is 17.