A conservation area is 300 acres. A researcher samples 6 random 1-acre plots and records tree counts of 60, 72, 68, 64, 75, and 70. Based on the mean of these samples, which range best estimates the total number of trees in the area?
18,000 to 19,000
20,000 to 21,000
20,500 to 21,500
21,000 to 22,000
