To calculate average velocity, the correct formula is Δx / Δt, not Δv / Δt. The user is struggling to find the exact position at t = 5, which lies between 40 and 60 on the graph. It is suggested to measure the graph accurately rather than estimating, as the graph is linear and indicates a constant velocity. One user points out that the values at t = 4.5 and t = 6 can be used to calculate the velocity at t = 5, which should yield a different result than the incorrect 6.3 previously calculated. Accurate measurement and understanding of the graph are crucial for solving the problem correctly.