Triathlete Dan runs along a 2-mile stretch of river and then swims back along the same route. If Dan runs at a rate of 10 miles per hour and swims at a rate of 6 miles per hour, what is his average rate for the entire trip in miles per minute?
Total Distance/Total time
=4/ [( 1/5) + (1/3)]= 15/2
in miles per minute 15/2*60 = 1/8