Mr. Vijay rows a boat with the stream in 8 km/hr and against the stream in 4…
2017
Mr. Vijay rows a boat with the stream in 8 km/hr and against the stream in 4 km/hr. In still water, his rate of rowing in km/hr is:
- A.
1
- B.
6
- C.
3
- D.
4
Attempted by 91 students.
Show answer & explanation
Correct answer: B
Given:
Speed with the stream (downstream) = 8 km/hr
Speed against the stream (upstream) = 4 km/hr
Let speed in still water = b km/hr and speed of the stream = s km/hr.
Downstream speed = b + s and upstream speed = b − s.
So: b + s = 8 and b − s = 4.
Adding the two equations: 2b = 12, so b = 6.
Speed in still water = 6 km/hr.