Pls help me :( I need a c in avid

For a study comparing leisure activities of physical education students with those of other students, a researcher has randomly selected a ten percent sample of physical education students and one percent sample of non-physical education students for a list of students. what kind of sampling technique is this?

Which tip applies to the aspire test and psat equally

Why are radio observatories located in valleys far away from urban centers? a. to shield them from electromagnetic interference b. to avoid sound pollution c. to avoid disturbing people living in the city d. to shield them from water vapor