If a motorboat moves upstream at the rate of 12 km/hr and downstream at the rate of 18 km/hr, then the speed of the current is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → 3 km/hr
Let u = speed of the boat in still water and v = speed of the current. Then downstream speed = u + v and upstream speed = u − v:
\(u+v = 18\)
\(u-v = 12\)
Subtracting:
\( \displaystyle 2v = 6, \quad v = 3 \text{ km/hr} \)