Answer:
5.45 mph
4.54 mph
Explanation:
8 ft/sec * 60 seconds/minute = 480 ft/minute
480 ft/minute * 60 minutes/hour = 28,800 ft/hr
28,800 ft/hr / 5280 ft/mil
20 ft/3 sec = 6.67 ft/sec
6.67 ft/sec * 60 seconds/minute = 400.2 ft/minute
400.2 ft/minute * 60 minutes/hour = 24,012 ft/hr
24,012 ft/hr / 5280 ft/mil = 4.54 mph