Answer :
Final answer:
The motorboat will take approximately 5.33 hours to cover the same distance against the stream.
Explanation:
In order to determine the time taken by the motorboat to cover the same distance against the stream, we first need to find the speed of the stream. We can do this by subtracting the speed of the motorboat in still water from the speed of the motorboat along the stream. Given that the motorboat travels 80 km in 1 hour 20 minutes, which is 1.33 hours, we can calculate the speed of the stream:
Speed of stream = Speed of motorboat along stream - Speed of motorboat in still water
Speed of stream = 80 km/1.33 h - 45 km/h
Speed of stream = 60 km/h - 45 km/h = 15 km/h
Now, we can calculate the time taken by the motorboat to cover the same distance against the stream:
Time = Distance/Speed
Time = 80 km/15 km/h
Time = 5.33 hours
Hence, the motorboat will take approximately 5.33 hours to cover the same distance against the stream.
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