A person can row downstream 49 km in 7 hours and upstream 36 km in 9 hours. What is the speed of the current?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 1.5 km/h.
Let the speed of boat in still water and speed of current be x and y respectively.
Now, downstream speed, x + y = 49/7
⇒ x + y = 7 ...(i)
Also, upstream speed, x - y = 36/9
⇒ x - y = 4 ...(ii)
Subtracting equation (ii) from equation (i),
⇒ 2y = 3
⇒ y = 1.5 km/h