10 mph
0.25 miles a minute, an average of 15 mph......................................
You would have to run 60 ÷ 8 = 7.5 mph.
You must maintain an average speed of 7.52 mph
Your average speed must be at least 8 mph.
You have to maintain a minimum average speed of 5.46 mph
15 mph, 4 minute mile
Your average speed must be at least 10 mph
Your average speed over the distance must be at least 16.2 mph
You have to maintain an average speed of 13.64 mph to achieve a 4 minute 24 second-mile time.
Pretty fast.
Just over 4.77 mph