Question

The speed of a boat in still water is 11km/hour .It can go 12km upstream and return downstream to the original point in 2hours 45minutes. Find the speed of the stream.​

Answer 1

kindly look at the provided photo for the answer.

Answer 2

Answer:

Let the speed of the stream be "x km/ hr.n

. Speed of boat in still water = 11 km/ hr.

Therefore, speed of boat upstream = 11 - x

speed of boat downstream = 11 + x

A.T.Q.,12 /11 -x +12/11+x= 2 3/4

⇒12 (1/ 11 -x+1/ 11 +x)= 11 / 4

⇒ 22 / 121 - x2 = 11 / 4*12

⇒ 22/ 121 - x2 = 11 / 48

⇒ 1331 -11 x2 = 1056

⇒ 11 x2 = 275

⇒ x2 = 25

⇒ x = + 5 or - 5

As speed can't be negative, x not equal to -5.

Therefore Speed of stream = x = 5 km / hr.

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