Find avrg speed if a man travels at speed of 15km/hr up and 28km/hr dawn at an altitude of 230m.	Answers.
A) 25.8 B) 19.5 C) 18.0 D) 12.2 E) 29.8

Rationale: "avg speed = 2 * x * y / ( x + y ) = 2 * 15 * 28 / ( 15 + 28 ) = 19.5 answer : b"
Answer: B