To estimate the number of seventh-graders expected to attend summer camp, we can use the proportion of students who attended summer camp in Russell's random survey.
In his survey:
- 6 out of 30 students attend summer camp.
To find the proportion of students attending summer camp, we calculate:
\[ \text{Proportion} = \frac{6}{30} = \frac{1}{5} \]
Now, we can use this proportion to estimate how many of the 200 seventh-graders in his school are expected to attend summer camp.
Expected number of students attending summer camp:
\[ \text{Expected number} = \text{Total number of students} \times \text{Proportion} = 200 \times \frac{1}{5} = 200 \div 5 = 40 \]
Therefore, about 40 students are expected to attend summer camp.
The answer is C. 40 students attend summer camp.