To determine the number of runners observed, we can count the entries in the distance list you've provided.
Based on your input, the distances are:
- Deon - 1 mile
- Tyrone - 85812 miles
- Darnell - 1/4 mile
- Blake - (not specified)
Since the distance for Blake is not provided, we can conclude there are three runners (Deon, Tyrone, and Darnell) for whom we have recorded distances. If Blake is included but with no distance, it could also be considered in the count.
Therefore, based on the provided information, there were at least three runners observed. If Blake is considered a runner, then the total would be four runners.