Given,
Distance, D=3km
Speed, V=6kmh−1
Time = Distance/ speed
t=DV=36=0.5hr=30min
Hence, in 30 min he reaches market from home.
A man walks on a straight road from his home to a market 2.5 km away with a speed of 5 km/h. Finding the market closed, he immediately turns and walks back home with a speed of 7.5 km/h. The average speed of the man over the interval of time 0 to 40 min is equal to: