A national survey of middle school students asks how many hours of sleep they get on school nights. Which sample best represents the population?
a.) A group of 941 students in eighth grade in a certain town
b.) A group of 886 students in sixth grade in a certain county
c.) A group of 795 students in seventh grade in different states
d.) A group of 739 students in different middle school grade levels from various states
It wouldnt be a single grade being surveyed so we would choose d in additon a and b isnt national since it says 'in a certain town' and 'in a certain county'.
