<PRE><B>Question 70213</B>
Let the speed of water current be x km/hr
So speed of boat in upstream = 25-x km/hr
speed of boat in downstream = 25+x km/hr
Now given that
T1:T2=2:3
where T1 is time taken by boat to cover 100 km in downstream
      T2 is time taken by boat to cover 100 km in upstream

so
T1/T2= (100/25+x)/(100/25-x)

now put T1/T2=2/3
so 
2/3=(100/25+x)/(100/25-x)
soving for x
we get x= 5km/hr 

so the speed of water current is 5km/hr

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