Find avrg speed if a man travels at speed of 24km/hr up and 36km/hr dawn at an altitude of 200m. Choose the correct choice from the following answers.
A) 25.8 B) 26.8 C) 27.8 D) 28.8 E) 29.8

Rationale: avg speed = 2 * x * y / ( x + y ) = 2 * 24 * 36 / ( 24 + 36 ) = 28.8 answer : d
Answer: D