Question
The ratio of the speed of the boat in upstream to that
in downstream is 5:9, respectively. If the speed of the current is 10 km/h, find the speed of the boat in still water.Solution
ATQ,
Let the speed of the boat in still water = x km/h Speed of the boat downstream = (x + 10) km/h Speed of the boat upstream = (x – 10) km/h According to the question: (x - 10):(x + 10) = 5:9 Cross-multiply: 9(x - 10) = 5(x + 10) Simplifying: 9x - 90 = 5x + 50 9x - 5x = 50 + 90 4x = 140 x = 35 km/h So, the speed of the boat in still water is 35 km/h.
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