An athlete runs 100 yards in 9 seconds. What is the rate of speed in mile per hours.
100 /9 =11.11 yards per second
1 mile =1,760 yards
11.11 x 60 minutes x 60 seconds=~40,000 yards in 1 hour
40,000 / 1,760 =22.73 mph, or miles per hour.
