Final answer:
To infer the number of non-working dry-erase board markers at the school, we apply the finding that 15% of markers do not work from the sample to the total number. Estimating with this method suggests that approximately 30 of the 200 dry-erase markers at the school are likely to be non-working.
Step-by-step explanation:
The student's question is about making an inference regarding the total number of non-working dry-erase board markers at Juan's school based on a random sample. From the provided sample, 9 out of 60 markers do not work, which represents 15% (9/60) of the markers. To estimate the number of non-working markers in the entire school, we can apply this percentage to the total number of markers in the school.
So, if 15% of the markers in the school are non-working, we would expect about 15% of the 200 markers to be non-working. Therefore, we calculate:
0.15 x 200 = 30
Based on this inference, we can predict that approximately 30 of the 200 dry-erase board markers at Juan's school do not work.