A man can row at 9 km/h in still water. When the river flows at 5 km/h, it takes him 2.4 hours to row to a certain place and return. How far is the place? (Rounded off to 2 decimal places)
7.47 km
Downstream speed = still-water speed + stream speed \(= 9 + 5 = 14\text{ km/h}\). Upstream speed \(= 9 - 5 = 4\text{ km/h}\).
Let the one-way distance be D km. Total time for the round trip: \(\dfrac{D}{14} + \dfrac{D}{4} = 2.4\).
Take the common denominator 28: \(\dfrac{2D}{28} + \dfrac{7D}{28} = \dfrac{9D}{28} = 2.4\).
Solve for D: \(D = \dfrac{2.4 \times 28}{9} = \dfrac{67.2}{9} \approx 7.47\text{ km}\).
Hence, the place is approximately 7.47 km away.
Similar Questions
A boatman is rowing on a river. He takes 4 hours to travel upstream and 2.5 hours to travel downstream. If the speed of the river’s current is 3 km/h, what is the boat’s speed in still water?
A boatman can travel 22 km downstream and 15 km upstream in 3 hours and 20 minutes. He can also travel 14 km downstream and 12 km upstream in 2 hours and 24 minutes. What is the speed of the boat in still water? (Round off your answer to two decimal places.)
A ship takes 15.5 hours for travelling downstream from point M to point N and coming back to a point P midway between M and N. If the speed of the stream is 3.5 kmph and the speed of the ship in still water is 11.5 kmph, what is the distance between M and N?
A man can row at 9.5 km/h in still water. When the river flows at 2 km/h, it takes him 4 hours to row to a certain place and return. How far is the place? (Round off the answer to two decimal places.)
A man can row at 8.5 km/h in still water. He finds it takes twice as long to row upstream as downstream for the same distance. Find the speed of the current.
A boat travels 45 km upstream in 9 hours and 72 km downstream in 6 hours. Find the speed of the stream.
S1, S2 and S3 are three shops in a straight line on a river, which flows at a constant speed from S1 towards S3. S2 is equidistant between S1 and S3. Seerat rows his boat to purchase an item from S1 to S2 and back in 12.5 hours and he can row from shop S1 to S3 in 9.5 hours. Compare the speed of his boat in still water to that of the river.
A motorboat travels 72 km downstream in 3 hours. The same boat takes 4 hours to cover 48 km upstream. What is the speed of the motorboat in still water?
The ratio of the speed of a boat to the speed of the current of water is 36 : 5. The boat goes a certain distance downstream in 5 hours 10 minutes. How much time will it take to come back against the stream?
Important Questions from Boat and River
A boat sails 15 km of a river towards upstream in 5 hours. How long (in hours) will it take to cover the same distance downstream, if the speed of river is one-fourth the speed of the boat in still water?
The speed of boat upstream is 5 kmph. Its speed in still water is 10 kmph. How many minutes will it take to row 25 km downstream?
Sudha can travel a certain distance downstream in 6 hours by boat and return to the starting point in 9 hours. If the stream flows at a speed of 3 km/h, how long (in hours) will it take to cover a distance of 67.5 km in still water?
The downstream speed of a boat is 20 km/hr and the speed of stream is 4 km/hr. What will be the total time taken by the boat to cover 160 km downstream and 96 km upstream?
The ratio of the speeds of a boat in still water and the speed of the river is 3 ∶ 1. The boat takes 45 minutes for a round trip journey. Find the distance of the whole trip if the speed of the stream is 4 km/hr.
