To estimate how many seventh graders at the school listen to music while doing homework, we can use the proportion we found in the survey.
From the survey:
- Total students surveyed = 20
- Students who listen to music while doing homework = 12
The proportion of students who listen to music while doing homework is:
\[ \text{Proportion} = \frac{12}{20} = 0.6 \]
Now, we apply this proportion to the total number of seventh graders in the school (245 students):
\[ \text{Estimated number of students} = 0.6 \times 245 \]
Calculating that,
\[ 0.6 \times 245 = 147 \]
Thus, we can estimate that about 147 seventh graders in the school listen to music while doing homework.