Jacob wants to know how many students in his school enjoy watching space travel programs on TV. He poses this question to all 20 students in his history class and finds that 80% of his classmates enjoy watching space travel programs on TV. He claims that 80% of the school's student population would be expected to enjoy watching space travel programs on TV. Is Jacob making a valid inference about this population?

Question

kpop_fan · Answer

No, it is not a valid inference because his classmates do not make up a random sample of the students in the school
 No, it is not a valid inference because he asked all 20 students in his history class instead of taking a sample from his math class 
Yes, it is a valid inference because his classmates make up a random sample of the students in the school 
Yes, it is a valid inference because he asked all 20 students in his history class

anonymous · Answer

The classroom would not represent the population since, its a single history class. You would need more variation than a class subject that represents more variation.

anonymous · Answer

The most logical answer would probably be A. Since the others mention that its either valid, or that it is not valid due to being 20 students.  A sample size could be 20 in some cases, but in this case it doesnt mention the school population so would couldnt know if 20 was too small.