A man inside a boat rows 9 km in on hour when rowing in still water. In a further part, the stream starts to flow. Now the person takes twice as much time to go upstream as he takes to go downstream. If the distance covered is same, can you find the speed of the stream?
A) 6 km/h B) 9 km/hr C) 3 km/hr D) 12 km/hr
Answers
hi
yr answer is
option A 6km/h
I hope it will help you
plz mark it a brainliest answer :)
Answer:3 km/h
Step-by-step explanation:
The distance is equal, let it be = d. Then let the speed upstream = d/2t and speed downstream = d/t as per the question. Now we have that the speed of the boat upstream: the speed of the boat downstream = 2:1
Let ‘r’ be the speed of the flow of the river and ‘b’ be the speed of the boat in still water.
Then the upstream speed of the boat = b – r.
Also, the downstream speed of the boat = b + r.
According to the given condition:
(b – r)/(b + r) = 2:1
Therefore, upon cross multiplication we have: 2b + 2r = b – r or b = -3r.
Since ‘b’ is the speed of the boat in still water, which is = 9 km/hr. Therefore, we have -3r = -(9) or r = 3 km/hr.
Neglecting the negative sign as this is the speed of the river, we have the speed of the stream = C) 3 km/hr.