Question
The speed of a boat in still water is three times the
speed of the boat upstream. If the boat takes 30 minutes to cover 27 km downstream, then find the speed of the boat in still water.Solution
Let the speed of the boat in still water be ‘3x’ km/h. Speed of the boat in upstream = 3x ÷ 3 = ‘x’ km/h Speed of the stream = 3x – x = ‘2x’ km/h Speed of the boat in downstream = 3x + 2x = ‘5x’ km/h ATQ. (27/30) × 60 = 54 So, 5x = 54 Or x = 10.8 So, speed of the boat in still water = 3 × 10.8 = 32.4 km/h
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