Question

Bill and Amy want to ride their bikes from their neighborhood to school which is 14.4 kilometers
away. It takes Amy 40 minutes to arrive at school. Bill arrives 20 minutes after Amy. How much
faster (in meters/second) is Amy’s average speed for the entire trip?
Be sure to show all necessary metric conversions!!

Answer 1

First we should convert 14.4 km into meters using the conversion factor 1km = 1000m; thus, 14.4 km = 14,400 m. Next, we should convert all minutes into seconds using the conversion factor 1 min = 60 seconds; thus, 40 mins = 2400 seconds while 20 minutes = 1200 seconds. 
Speed = distance over time
Amy's speed = 14400 m / 2400 sec = 6m/s
Bill's time is 1200 sec + Amy's which is 2400 sec
Bill's speed = 14400m / 3600 sec  = 4 m/s

Therefore, Amy is faster than Bill with 2 m/s difference.