I am doing this question, and have collected the times and distances traveled at those various times. I am supposed to calculate the average velocity for each distance now. The book say: vav = vinst = d/t ; at t’ = t/2 (half time) But I checked online and found: vav = (d2 – d1)/(t2 – t1) Earlier in the book, it indicated that it was: vav = d/t. Which is it?! This doesn't make sense to me!