A boat can move upstream at 25 km/h and downstream at 35 km/h. What is the speed of the current?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 5 km/h.
Let the speed of boat in still water be x km/h and speed of current be y km/h.
Upstream speed = x - y
Downstream speed = x + y
According to the given question,
x + y = 35 ... (i)
And x - y = 25 ...(ii)
Subtracting equation (ii) from equation (i),
⇒ 2y = 10
⇒ y = 5 km/h