Speed from a distance vs. time graph

[ravsterphysics]

Homework Statement

Homework Equations

The Attempt at a Solution

I know velocity = distance/time and the steepest gradient means the maximum speed, and the gradient is steepest between 1 and 1.5 seconds with the change in distance being around 40cm so velocity = 40cm/0.5 = 80 cm per second.

So my answers are nowhere near what they want.

Where am I going wrong?

 

[TSny]

You want an estimate of the maximum instantaneous speed. You might need to "zoom in" to a much smaller interval of time where the graph is steepest.