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36. The speed of a motor boat in still water is 15 km/hour. If it goes down thestream 30km and again returns to the starting point in a total time of 4 hours and30 minutes. Find the speed of the stream. |
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Answer» Let the speed of the stream be x km/hr. Then, Speed downstream = (15 + x) km/hr,Speed upstream = (15 - x) km/hr.Therefore,30/(15+x) + 30/(15-x) = 4(1/2)=> 900/(225-x^2) = 9/2=> 9x^2 = 225=> x^2 = 25=> x = 5 |
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