Correct Answer - Option 1 : 40
Given:
A boat makes a round trip of 240 km in 13 hours when the speed of the stream is 14 km/hour
Formula:
Upstream = (u − v) km/hr
where “u” is the speed of the boat in still water
“v” is the speed of the stream
Downstream = (u + v) Km/hr
where “u” is the speed of the boat in still water
“v” is the speed of the stream
Speed of Boat in Still Water = (1/2)(Downstream Speed + Upstream Speed)
Speed of Stream = (1/2)(Downstream Speed – Upstream Speed)
Calculation:
Let the speed of the boat in still water be x km/hr
Upstream Speed = x - 14
Downstream Speed = x + 14
{120/(x - 14)} + {120/(x + 14)} = 13
⇒ x = 26
Downstream speed = x + 14 = 40 km/h
∴ The downstream speed is 40 km/h.
