Q. 254.2( 6 Votes )

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Answer :

Let the speed of the stream be x km/hr

Speed of the boat upstream =( 20 – x )km/hr

Speed of the boat downstream =( 20 + x)km/hr

Distance =48km (given).

me taken in journey upstream =. hr

Time taken in journey upstream =hr

Time(upstream)-Time(downstream) =1hr (given)

96x=(20-x)(20 + x)


x2 + 96x-400=0

x2 + 100x-4x-400=0

x(x + 100)-4(x + 100)=0

(x-4)(x + 100)=0

Possible values of x are x=4 and x=-100

Rejecting the negative value of x,

Speed of stream =4km/hr


(taking LCM)

-30=(x + 4)(x-7)


X2-3x + 2=0

X2-2x-x + 2=0



x=-1 or x=-2

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