Question 25

The sum of the speed of the boat A downstream and the speed of the boat B upstream is 27km/h. If the speed of boat A in still water is 3km/h less than that of boat B, what is the respective ratio between the speed of boat A in still water and that of boat B in still water? (Considering the speed of current to be constant)

Solution

Let speed of boat A in still water = $$x$$ kmph

=> Speed of boat B in still water = $$(x + 3)$$ kmph

Let speed of current = $$y$$ kmph

Acc to ques,

=> $$(x + y) + (x + 3 - y) = 27$$

=> $$2x = 27 - 3 = 24$$

=> $$x = \frac{24}{2} = 12$$ kmph

Speed of B = 12 + 3 = 15 kmph

$$\therefore$$ Required ratio = 12 : 15

= 4 : 5

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