Question
Speed of a boat in still water is 5 times more than the
speed of stream. If boat covers 147 km in downstream in 7 hours, then find the time taken by the boat to cover 135 km in upstream.Solution
Let the speed of stream be ‘x’ km/hr. So, speed of boat in still water = 6 × x = 6x km/hr Downstream speed of boat = 6x + x = 7x km/hr According to question; 7x = 147/7 = 21 Or, x = 3 Upstream speed of the boat = 6x – x = 5x = 5 × 3 = 15 km/hr Required time taken = 135/15 = 9 hours
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