1. The problem statement, all variables and given/known data The problem is in the provided link (it is questions 2.2) http://www.docstoc.com/docs/3817109/Chapter-Problems-A-car-travels-up-a-hill-at-a 2. Relevant equations 3. The attempt at a solution I understand the duration of time it takes to go up the hill is a larger time interval than going down; but I fail to see that fact as a viable way to justify not just simply adding the to velocities and dividing by two. Could someone please understand this part to me, thank you.