Question
A boat covers 72 km upstream and 108 km downstream in 6
hours and 4.5 hours, respectively. Find the time taken by the same boat to cover 150 km in still water.Solution
ATQ, Let speed of the Boat in still water be ‘x’ km/h and speed of the stream be ‘y’ km/h Upstream speed of boat = (x – y) = (72/6) = 12 km/h --------- (I) Downstream speed of boat = (x + y) = (108/4.5) = 24 km/h ---------- (II) On adding equation (I) and equation (II), we have: 2x = 36 Or, x = 18 So, speed of the Boat in still water = 18 km/h Therefore, time taken by the Boat to cover 150 km in still water = (150/18) = 8.33 hours
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