Triathlete Dan runs along a 3-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? Choose the correct choice from the following choices:
A) 1 / 8  B) 2 / 15  C) 3 / 15  D) 1 / 4  E) 3 / 8

Rationale: "dan travels 6 miles round trip . running part : ( 3 / 10 * 60 = 18 minutes ) swimming part : ( 3 / 6 * 60 = 30 minutes ) 6 miles in ( 18 + 30 ) minutes 6 / 48 = 1 / 8 mile per minute answer : 1 / 8 mile per minute a"
Answer: A