1. The problem statement, all variables and given/known data Given the following formula for distance, find the average velocity on the interval [1,3] S(t) = t/(1+t^2) 2. Relevant equations Vavg = (S(t0) - S(t1)) / (t0 - t1) or Vavg = (V0 + V1)/2 3. The attempt at a solution I get two different answers and I need help understand why. Vavg = (S(1) - S(3)) / (1-3) Vavg = (1/2 - 3/10) / -2 Vavg = -2/20 = -1/10 Now using a different method, getting the instantaneous velocity at t = 1 and t = 3 by taking derivative of S(t) -> S'(t) = (1-t^2)/(1+t^2)^2 Vavg = (S'(1) + S'(3))/2 Vavg = (-8/100)/2 = (-2/25)/2 = -1/25 Why am I getting different averages here?? I don't understand what I'm doing wrong.