It should be set at 6 miles per hour. This will give a time of 20 minutes for two miles.
If you run 2.5 miles in 20 minutes your average speed is 7.5 miles per hour.
1.5 miles/12 minutes = 7.5 miles/hour
Your avarage speed would be 12 miles an hour.
Your average speed is 10 miles per hour.
Your average speed is 11.25 miles per hour.
Set the treadmill at 6.6 mph
You ran 1.2 miles.
6 miles in 40 minutes is 3 miles in 20 minutes. Since 20 minutes fits into 60 minutes 3 times, the speed would be 9 miles an hour.
To run 1.5 miles in 12.5 minutes you must maintain an average speed of 11.6 km/h
Two miles in 16 minutes requires an average speed of 7.5 miles per hour.