A motor boat whose speed in still water is 15 km/h goes 40km downstream and comes back in a total time of 6 hours. find the speed of the stream
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let speed of stream is x km/h
then speed of boat in downstream is (15+x) km/h and in upstream is (15-x) km/h
acc to ques
40/(15+x) + 40/(15-x) = 6
40[1/(15+x)+1/(15-x)]=6
40[15-x+15+x]=6(225-x^2)
40×30= 1350 - 6x^2
6x^2 = 1350-1200
x^2= 150/6
x^2 = 25
x= 5
then speed of boat in downstream is (15+x) km/h and in upstream is (15-x) km/h
acc to ques
40/(15+x) + 40/(15-x) = 6
40[1/(15+x)+1/(15-x)]=6
40[15-x+15+x]=6(225-x^2)
40×30= 1350 - 6x^2
6x^2 = 1350-1200
x^2= 150/6
x^2 = 25
x= 5
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