80% of students who study receive high grades.
80% of students who receive high grades study a lot.
80% of the variation in GPAs can be explained by variation in number of study hours.
20% of the variation in GPAs cannot be explained by variation in number of study hours per day.
64% of the variation in GPAs can be explained by variation in number of study hours per day.
I and II
I and III
II and III
I, II and III
Yes, because every students has the same chance of being selected.
Yes, but only if there is a single entrance to the school.
Yes, because the 24 out of every 25 students who are not selected will form a control group.
Yes, because this is an example of systematic sampling, which is a special case of simple random sampling.
No, because not every sample of the intended size has an equal chance of being selected.