814 - Math - Problem Solving

Question: His speed during the second part was twice as that of the speed during the first part of the journey. What is his average speed of journey during the entire travel?

1. His average speed is the harmonic mean of the individual speeds for the two parts.
2. His average speed is the arithmetic mean of the individual speeds for the two parts.
3. His average speed is the geometric mean of the individual speeds for the two parts.
4. Cannot be determined.