Question
A boat travels downstream and then returns upstream but
only up to 60% of the downstream distance. The total journey takes 18 hours. The downstream speed is 25% more than the speed of the boat in still water. If the stream flows at 6 km/h, find the total distance covered by the boat.Solution
ATQ,
Let the speed of the boat in still water = x km/h Downstream speed = x + 6 = 1.25x 0.25x = 6 x = 24 km/h Downstream speed = 24 + 6 = 30 km/h Upstream speed = 24 – 6 = 18 km/h Let the distance covered downstream = y km Then upstream distance = 0.6y km According to question: y/30 + 0.6y/18 = 18 y/30 + 1y/30 = 18 (2y / 30) = 18 y = 270 km Total distance = 1.6 × 270 = 432 km
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