Sanjana can row a boat at 9 km/h in the still water. It takes her twice as long to row up a certain distance as to row down the same distance in the river. What is the rate of the stream (in km/h)?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 3.
Let the rate of the stream = x km/h and the distance Sanjana rows = D km
So, D/(9 - x) = 2[D/(9 + x)]
⇒ 1/(9 - x) = 2/(9 + x)
⇒ 9 + x = 18 - 2x
⇒ 3x = 9
⇒ x = 3
Therefore, the rate of the stream is 3 km/h.