About 90 seconds maximum.
14.05 mph
11.1014 mph
3.19 MPH
19.2839 mph
9.77 mph
At 4 mph, you would cover 88 yards in one minute. In 45 seconds, you would cover 66 yards (88 multiplied by 0.75).
60 seconds = 1 minute = 1/60 hour. 0.25 miles per minute = 0.25 x 60 = 15 mph
Denard Robinson can run a 40 yard dash in 4.23 seconds, by this we can gather he runs 28.4 ft/s so if you do the math correctly he can run just about 19.4 MPH.
At least 16.8 mph
22.5 seconds.
The best male 400 hurdlers run about 2 seconds slower and the women run about 3. The average difference for an efficient hurdler is about 5 seconds for guys and 7 seconds for girls