Average speed =

 Substitute distance = 500 feet and time = 60 seconds

  Average speed =            

  1 hour = 60 minutes  

1 minute = 60 Seconds 

So, 1 hour = 60 × 60 Seconds 

1 hour = 3600 seconds 

Average speed =  

Average speed       

Average speed=  

Average speed= 30000 feet/hour            (Simplify) 

Replace feet’s with

=    

 =                                         (Divide: )

Average speed= 5.682 miles/hour