Answer: the average number is
1667 prairie dogs per square mile.
Explanation:
The largest colony of black-tailed prairie dogs contains 400 million prairie dogs on 24,000 square miles of land.
To determine the average number of prairie dogs for each square mile, we would divide the total population of prairie dogs by the total area of land on which they at found. It becomes
400000000/240000 = 1666.6667
Approximately 1667 prairie dogs per square mile.