In Amelia’s training schedule, her longest run in week 16 will be 26 miles and her longest run in week 4 will be 8 miles. Thus, Amelia increases the distance of her longest run by 18 miles over the course of 12 weeks. Since Amelia increases the distance of her longest run each week by a constant amount, the amount she increases the distance of her longest run each week is
26−8
16
−4=
18
12
=
3
2
=1.5 miles Choices A, B, and C are incorrect because none of these training scheduleswould result in increasing Amelia’s longest run from 8 miles in week 4 to 26 miles in week 16. For example, choice A is incorrect because if Amelia increases the distance of her longest run by 0.5 miles each week and has her longest run of 8 miles in week 4, her longest run in week 16 would be 8+0.5∙12=14 miles, not 26 miles.