That's the formula for average acceleration. Average velocity is [itex]\Delta x / \Delta t[/itex].sfgradv said:delta v over delta t.
Get out a ruler, and carefully measure (a) the distance between the x = 40 and x = 60 lines on the graph, and (b) the distance between the x = 40 line and the point where the graph intersects the t = 5 line. That will give you enough information to calculate x at t = 5 (more precisely, x - 40).sfgradv said:the thing is it doesnt tell u exactly what the position is at t = 5. it is between 40 - 60 and it said not to eyeball it. i thought it was 45 and i used it in the formula and got 6.3 and got the wrong answer. so what should i do now?