Question

solved it now..this is chalenging question..if u can solve then solved..i challenge u anybody can not sokved this question..CHALLEGE..?

Answer 1

Let the speed of still water be x km/h
Let the speed of stream be y km/h.
Now,
Speed of upstream = (x-y) km/h
Speed of downstream = (x+y) km/h

Never challenge..

Answer 2

let the speed of the stream be = u km/hour.
let the speed of the boat be =v km/hour .
speed upstream will be v-u km/hr
speed downstream will be v + u km/hour.

30 km upstream in time duration =30/(v-u) hrs
44 km downstream in time duration = 44 /v+u

44 / (v+u) + 30/(v-u) = 10 hrs ....(1)
similarily , 40 /v-u + 55 / v+u =13 hrs.
30 / (v-u) + 165 /4 (v + u) =39/4......(2)
Now ,( 1 ) -( 2 ) = 44 -(165 /4 ) / (v +u) = 10 -39 /4=1/4
= v+u =11 ......(3)
substitute this in (1) to get :
44/11 +30/v+u =10
v-u= 30/6 =5 ........(4)
we get v = 8 km / h and u= 3 km/hr