Answer:
The time required for this round trip is 1066.66 s
Explanation:
Given;
velocity of boat through still water, v₁ = 20 m/s
distance moved by the boat, d = 10 km = 10,000 m
velocity of the river, v₂ = 5 m/s
time = d / v
The boat made two journeys which formed the round trip.
During the first part of the journey, the boat moves upstream in opposite direction to the flow of the river and the resultant velocity is calculated as;
Resultant velocity = 20 - 5 = 15 m/s
Time for this journey, = 10000/ 15 = 666.66 s
During the second part of the journey, the boat moves downstream in the same direction to the flow of the river and the resultant velocity is calculated as;
Resultant velocity = 20 + 5 = 25 m/s
Time for this journey, = 10000/ 25 = 400 s
Total time for the trip = 666.66 s + 400 s = 1066.66 s
