Question
The speed of a boat in still water is 4 times more than
that of the current. If the boat takes 9 hours to cover 108 km upstream, then find the time taken by the boat to cover 522 km downstream.Solution
Let the speed of the current be ‘x’ km/hr
Therefore, speed of the boat in still water = 5x km/hr
According to the question,
5x – x = 108 / 9
Or, 4x = 12
Or, x = 3 km/hr
Required time taken = 522 / (5x + x) = 522 / (6 × 3) = 522/18 = 29 hours
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