A survey-inference question tests generalization: which group a result can reasonably describe. Identify the students who actually answered, then keep the reported percentage tied to that group. A claim about students who weren't surveyed, or a comparison between groups when only one was surveyed, goes beyond the evidence. This is a question about groups, not arithmetic.
Hints
- Hint 1
The sample is the group that answered the survey, not everyone who attends the school. Find the condition every interviewed student met. What does that tell you about the group the sleep result describes?
- Hint 2
A population is a larger group you want to describe. Comparing two groups requires sleep data from both groups; data from only one group can't establish which sleeps more. What would you need to support that comparison?
Step-by-step
Keep the survey result with its group
Step 1Identify who answered
No Desmos needed. The question asks who was surveyed, not for a calculation. The sample is the group that answered: 150 Central High students who participate in at least one after-school sport. So the describes answers from those students.
- Step 2
Set the limit of the result
Keep a survey percentage tied to the group that was surveyed. No nonparticipants were interviewed, so the result can't give their sleep percentage or show whether they sleep more or less than participants. All Central High students includes nonparticipants, so the result can't give a schoolwide percentage either.
- Step 3
Choose the supported inference
The matching inference, or conclusion drawn from the survey, is that about of Central High students who participate in after-school sports sleep at least hours on school nights. “About” treats the survey percentage as an estimate, not a guaranteed exact percentage for the whole group. Choice D.