Question

speed of a boat in still water is 11 kilometre per hour it can go 12 kilometre upstream and return downstream to the original pointing towards 45 minutes find the speed of the stream

Answer 1

 Let the speed of stream be x

Speed of boat in still water = 11
Speed of boat upstream = 11-x
Speed of boat downstream = 11+x

Distance = 12
Distance/speed = time

12/(11-x) + 12/(11+x) = 2 hours 45min
12*(22/(121-x^2) = 11/4
x^2 = 25
x = 5

Speed of stream = 5km/hr

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Answer 2

Let the speed of the stream be X km/hr.

speed of the boat in still water=11km/hr.

speed of the boat upstream =(11-X) km /hr.

speed of the boat downstream =(11+X)

distance =12km

12/(11-X)

12/(11+x)

12/(11-x) +12(11+x)=2 45/60

2[11-x+11+x]/121-x^2=11/4

12 x22/121xx^2=11/4

121-x^2=96

x^2=25

x=5