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- Question
- A boat's man goes 48 km downstream in 8 hours and returns back in 12 hours. Find the speed of the boat in still water and the rate of the stream?
Options- A. 5 km/hr; 1 km/hr
- B. 10 km/hr; 2 km/hr
- C. 6 km/hr; 1.5 km/hr
- D. None of these
- Correct Answer
- 5 km/hr; 1 km/hr
ExplanationRate downstream = 48/8 = 6 km/hr
Rate upstream = 48/12 = 4 km/hr
? Speed of boat in still water = (6 + 4)/2 = 5 km/hr
Rate of stream = (6 -4)/2 = 1 km/hr - 1. A man can row 44 km downstream in 4 hours. If the man's rowing rate in still water is 8 km/hr, then find in what time will he cover 25 km upstream?
Options- A. 5 hours
- B. 6 hours
- C. 4.5 hours
- D. 4 hours Discuss
- 2. A man can row at 5 km/hr in still water and the velocity of current is 1 km/hr. It takes him 1 hour to row to a place and back. How far is the place?
Options- A. 2.5 km
- B. 2.4 km
- C. 3 km
- D. 3.6 km Discuss
- 3. A man rows upstream 16 km and downstream 28 km talking 5 hours each time. The velocity of the current is?
Options- A. 2.4 km/hr
- B. 1.2 km/hr
- C. 3.6 km/hr
- D. 1.8 km/hr Discuss
- 4. A boat moves upstream at the rate of 1 km in 10 minutes and downstream at the rate of 1 km in 6 minutes. The speed of the current is?
Options- A. 1 km/hr
- B. 1.5 km/hr
- C. 2 km/hr
- D. 2.5 km/hr Discuss
- 5. The current of a stream runs at the rate of 4 km/hr. A boat goes 6 km and back to the starting point in 2 hours. The speed of the boat in still water is?
Options- A. 6 km/hr
- B. 7.5 km/hr
- C. 8 km/hr
- D. 6.8 km/hr Discuss
- 6. A man can row 60 km downstream in 6 hours. If the speed of the current is 3 km/hr, then find in what time will he be able to cover 16 km upstream?
Options- A. 4.5 hours
- B. 4 hours
- C. 5 hours
- D. 5.5 hours Discuss
- 7. speed of a boat in standing water is 7 km/hr and the speed of the stream is 1.5 km/hr. A distance of 7.7 km. going upstream is covered in?
Options- A. 1 hr. 15 min.
- B. 1 hr. 12 min.
- C. 1 hr. 24 min.
- D. 2 hr. 6 min. Discuss
- 8. A sailor sails a distance of 48 km along the flow of a river in 8 h. If it takes 12 h to return the same distance, then the speed of the flow of the river is?
Options- A. 0.5 km/h
- B. 1 km/h
- C. 1.5 km/h
- D. 2 km/h Discuss
- 9. Sameer can row a certain distance downstream in 24 h and can come back covering the same distance in 36 h. If the stream flows at the rate of 12 km/h, find the speed of Sameer in still water?
Options- A. 30 km/h
- B. 15 km/h
- C. 40 km/h
- D. 60 km/h Discuss
- 10. Pawan can row 24 km/h in still water. When the river is running at 4.8 km/h, it takes him 1 h to row to a place and to come back. How far is the place?
Options- A. 11.52 km
- B. 14 km
- C. 12.52 km
- D. 15 km Discuss
Boats and Streams problems
Search Results
Correct Answer: 5 hours
Explanation:
? Man's rate in still water = (man's rate with current + his rate against current)/2
? 8 = 1/2 [ 44/4 + 25/T ]
? 16 = 11 + 25/T
? T = 5 hours
Correct Answer: 2.4 km
Explanation:
Speed downstream = (5 + 1) km/hr = 6 km/hr
Speed upstream = (5 - 1) km/hr = 4 km/hr
Let the required distance be d km
Then, d/6 + d/4 = 1
? 2d + 3d = 12
? d = 2.4 km
Correct Answer: 1.2 km/hr
Explanation:
Speed downstream = (28/5) km/hr = 5.6 km/hr
Speed upstream = (16/5) km/hr = 3.2 km/hr
Velocity of current = (5.6 - 3.2)/2 km/hr = 1.2 km/hr
Correct Answer: 2 km/hr
Explanation:
Speed upstream = 6 km/hr
Speed downstream = 10 km/hr
? Speed of the current = (10 - 6)/2 km/hr = 2 km/hr
Correct Answer: 8 km/hr
Explanation:
Let the speed in still water be x km/hr
Then, 6/x + 4 + 6/x - 4 = 2
? 6[ x - 4 + x + 4] = 2(x2 - 16)
? x2 - 6x - 16 = 0
? (x - 8) (x + 2) = 0
? x = 8 km/hr
Correct Answer: 4 hours
Explanation:
Downstream speed = 60/6 = 10 km/hr
Speed of stream = 3 km/hr
Upstream speed = 10 - (2 x 3) = 4 km/hr
? Required time = 16/4 = 4 hours.
Correct Answer: 1 hr. 24 min.
Explanation:
Upstream speed = 7 - 1.5 = 5.5 km/hr
? 5.5 x T = 7.7
? T = 77.7 / 5.5 = 1hr. 24 minutes
Correct Answer: 1 km/h
Explanation:
Let speed of the flow of water be x km/h and rate of sailing of sailor be y km/h.
Downstream speed (x + y) = 48/8
? x + y = 6 ....(i)
and upstream speed x - y = 4 ...(ii)
On solving Eqs. (i) and (ii), we get
y = 1 km/h
Correct Answer: 60 km/h
Explanation:
Let the speed of Sameer in still water be x km/h
Sameer's speed downstream = (x + 12) km/h
Sameer's speed upstream = (x - 12) km/h
According to the question, 24(x + 12) = 36(x - 12)
? 2x + 24 = 3x - 36
? x = 36 + 24 = 60 km/h
Correct Answer: 11.52 km
Explanation:
Pawan's speed downstream = 24 + 4.8 = 28.8 km/h
Pawan's speed upstream = 24 - 4.8 = 19.2 km/h
Let the required distance be x.
According to the question.
x/28.8 + x/19.2 = 1
? (19.2x + 28.8x) / 552.96 = 1
? 19.2x + 28.8x = 552.96
? 48x = 552.96
? x = 552.96/48 = 11.52 km
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