Correct Answer - Option 1 : 5.6 Km/hr
Given:
A man coves 70% of distance at the speed of 5 km/hr and remaining distance at the speed of 8 km/h
Formula/Concept used:
Speed = Distance/time
Average speed = (Total distance)/Total time
Calculation:
Let the total distance be D and let the time when a man covers 70% distance in time t1 and remaining distance in time t2
When a man covers 70% distance at the speed of 5 km/hr
∴ 5 = (7D/10)/t1
⇒ t1 = 7D/50
And when a man covers remaining distance at the speed of 8 km/hr
∴ 8 = (3D/10)/t2
⇒ t2 = 3D/80
Now, average speed = D/[(7D/50) + (3D/80)] = 5.6 Km/hr
∴ The average speed of a man is 5.6 Km/hr