If a man climbs a hill at 6 km/h on the journey from foot to top of the hill and returns at 10 km/h, then find his average speed for the journey (in km/h).
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 7.5
A man climbs up a hill during the journey with a speed of X = 6 km/h
During the return of journey, his speed of Y = 10 km/h
According to the question
The average speed = 2XY/(X + Y)
The average speed = 2 × 6 × 10/(6 + 10) = 120/16 = 7.5 km/h