Question
In still water, boats A and B have speeds in the ratio
15:11. Boat A’s still-water speed is five times the stream speed. If A covers 180 km downstream in 5 hours, find the time taken by B to travel 96 km upstream.Solution
ATQ, Let the speeds be 15x and 11x km/hr Stream speed = 15x/5 = 3x Downstream speed of A = 15x + 3x = 18x 180/5 = 36 ⇒ 18x = 36 ⇒ x = 2 Required time = 96/(11x – 3x) = 96/(8x) = 96/16 = 6 hours
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