This Problem Set is a part of the Lesson 18, Unit 8, Grade 7. Lin wants to know if students in elementary school generally spend more time playing outdoors than students in middle school. She selects a random sample of size 20 from each population of students and asks them how many hours they played outdoors last week. Suppose that the MAD for each of her samples is about 3 hours. Select all pairs of sample means for which Lin could conclude there is a meaningful difference between the two populations.