please help 10 points. Only answer 3 and 4 please. And also only answer if you know it pleasssssssss.

Answer:
3. Walter's sample is not representative. 4. The population is his community service group.
Step-by-step explanation:
3. His sample is not representative because the survey was only on his math class, not the whole entire population. This sample only represents his math class.
4. The population is his community service group that is what class he is surveying 15 members from.
Hope this helped!