Ravish rowed 40 km downstream in 2 hrs 30 min and returned to the starting point in 5 hrs. What is the speed of the current ?
Answer & explanation
Correct answer: option 4
Distance $=40$ km.
Downstream time $=2$ hr $30$ min $=\frac{5}{2}$ hr.
Downstream speed $=\frac{40}{\frac{5}{2}}=16$ km/hr.
Upstream time $=5$ hr.
Upstream speed $=\frac{40}{5}=8$ km/hr.
Speed of current $=\frac{16-8}{2}=4$ km/hr.
final answer: $4$ km/hr