Question
A boat travels 100 km upstream and 160 km downstream in 9
hours. If the speed of the boat in still water is 25 km/hr greater than the speed of the stream, calculate the stream's speed.Solution
ATQ,
Let the speed of the stream = x
And the speed of the boat in still water = x + 25
100/(x + 25 – x) + 160/(x + 25 + x) = 9
100/25 + 160/(2x + 25) = 9
4 + 160/(2x + 25) = 9
160/(2x + 25) = 9 – 4
160/(2x + 25) = 5
2x + 25 = 160/5
2x + 25 = 32
2x = 32 – 25
2x = 7
x = 7 / 2
x = 3.5
The speed of the stream = 3.5 km/hr
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