Question
A boat takes 16 minutes and 24 minutes to cover a
certain distance downstream and upstream, respectively. If the speed of the boat in still water is 15 km/h, find the speed of the stream.Solution
Let's assume the speed of boat in still water and the speed of stream are 'B' and 'C' respectively. If the speed of the boat in still water is 15 km/h. So B = 15Â Â km/h. A boat takes 16 minutes and 24 minutes to cover a certain distance downstream and upstream, respectively. downstream speed of boat = (B+C) = distance / time (15+C) = distance / (16/60) [Here time is converted into hours.] distance = (15+C) x (16/60)Â Â Eq.(i) upstream speed of boat = (B-C) = distance / time (15-C) = distance / (24/60) [Here time is converted into hours.] distance = (15-C) x (24/60)Â Â Eq.(ii) So Eq.(i) = Eq.(ii). (15+C) x (16/60) = (15-C) x (24/60) (15+C) x 2 = (15-C) x 3 30+2C = 45-3C 2C+3C = 45-30 5C = 15 C = 3 Speed of the stream = C = 3 km/h
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