The training model uses a deterministic scale, not a simulated path. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
A persistence time is a scale
The checked claim is still speed 4 times time 3 equals run 12.
4⋅3=12
Do not infer a sampled path
The diagram gives one deterministic scale, not a random track or cell-signaling model.