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A man can row at 10 km/h in still water. If he takes total 5 h to go to a place 24 km away and return, then the speed of the water current is

A) 2 km/h
B) 3 km/h
C) \( \Large \frac{1}{2} \) km/h
D) 1 km/h

Correct Answer:

A) 2 km/h

Description for Correct answer:
Let speed of water current be x km/h.

Speed downstream = (10 + x) km/h,

water = (10 x) km/h

According to the question,

\( \Large \frac{24}{10+x}+\frac{24}{10-x}=5 \)

= \( \Large 24 \left(10-x+10+x\right) = 5 \left(10^{2} - x^{2}\right) \)

= \( \Large 100 - x^{2} = \frac{24 \times 20}{5} \)

= \( \Large 100 - x^{2} = 96 \)

= \( \Large x^{2} = 4 \)

= \( \Large x = \sqrt{4} \) = 2 km/h

Part of solved Boat and Stream questions and answers : >> Aptitude >> Boat and Stream

Comments

Similar Questions

1). A steamer goes downstream from one port to another in 4 h. It covers the same distance upstream in 5 h. If the speed of the stream is 2 km/h, then find the distance between the two ports.

A). 50 km

B). 60 km

C). 70 km

D). 80 km

2). A man can row \( \Large 7\frac{1}{2} \) km/h in still water. If in a river running at 1.5 km/h, it takes him 50 min to row to a place and back, how far off is the place?

A). 3 km

B). 4 km

C). 1 km

D). 2 km

3). Ashutosh can row 24 km/h in still water. It takes him twice as long to row up as to row down the river. Find the rate of stream.

A). 4 km/h

B). 18 km/h

C). 8 km/h

D). 15 km/h

4). A boat goes 12 km in 1 h in still water. It takes thrice time in covering the same distance against the current. Find the speed of the current.

A). 8 km/h

B). 12 km/h

C). 6 km/h

D). 7 km/h

5). A boatman takes twice as long to row a distance against the stream as to row the same distance with the stream. Find the ratio of speeds of the boat in still water and the stream.

A). 2 : 1

B). 3 : 1

C). 1 : 2

D). 1 : 3

6). A boat running upstream takes 528 min to cover a certain distance, while it takes 240 min to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current, respectively?

A). 2 : 1

B). 3 : 2

C). 8 : 3

D). Couldn't be determined

7). A river is flowing with a steady speed of 4 km/h. One rows his boat downstream in the river and then returns by rowing upstream in the same river. When he returns to the starting point, the total distance covered by him is 42 km. If the return journey takes 2 h more than his outward journey, then the speed of his rowing in still water must be

A). 12 km/h

B). 10 km/h

C). 9 km/h

D). 8 km/h

8). The ratio of speeds of a motorboat to that of the current of water is 36 : 5. The motorboat goes along with the current in 5 h 10 min. Find the time to come back of motorboat.

A). 5 h 50 min

B). 6 h

C). 6 h 50 min

D). 12 h 10 min

9). Ishwar is rowing a boat. He takes half time in moving a certain distance downstream than upstream. What is the ratio of the rate of boat in still water to the rate of current?

A). 2 : 1

B). 5 : 1

C). 7 : 1

D). 3 : 1

10). In a river, the ratio of the speed of stream and speed of a boat in still water is 2 : 5. Again, ratio of the speed of stream and speed of an another boat in still water is 3 : 4. What is the ratio of the speeds of the first boat to the second boat in still water?

A). 10 : 7

B). 15 : 8

C). 4 : 3

D). 5 : 4