Question
The downstream speed of a boat is 8 km/hr more than its
upstream speed and the ratio of the speed of the boat in still water to the speed of the stream is 9:4. Find the total time taken by boat to travel 39 km downstream and 25 km upstream? Section 2Solution
Let the speed of boat in still water be x km/hr and that of stream be y km/hr. ATQ, ⇒ (x + y) – (x – y) = 8 ⇒ y = 4 km/hr ⇒ x = 4 × 9/4 = 9 km/hr Required time = [39/(9+4)] + [25/(9−4)] = 8 hr
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