The centroid must remain inside the checked cluster span. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
The span comes from the endpoint positions
The cluster endpoints are 1 meter and 2 meters.
1m≤x≤2m
The centroid must lie inside that span
The centroid 5 over 4 meters is between the endpoints.