Boats and Streams problems
- 1. The speed of a boat downstream is 15 km/hr and the speed of the stream is 1.5 km/hr. The speed of the boat upstream is?
Options- A. 13.5 km/hr
- B. 16.5 km/hr
- C. 12 km/hr
- D. 8.25 km/hr Discuss
Correct Answer: 12 km/hr
Explanation:
Let the speed of boat in still water be x km/hr
Then, x + 1.5 = 15
? x = 13.5
? Speed upstream = (13.5 - 1.5) km/hr = 12 km/hr
- 2. The speed of a boat in still water is 2km/hr. If its speed upstream be 1 km/hr, then speed of the stream is?
Options- A. 1.5 km/hr
- B. 3 km/hr
- C. 1 km/hr
- D. None of these Discuss
Correct Answer: 1 km/hr
Explanation:
Let the speed of stream be x km/hr
Then, speed upstream = (2 - x ) km/hr
? 2 - x = 1
? x = 1 km/hr
- 3. A man can row downstream at 14 km/hr and upstream at 9km/hr. Man's rate in still water is?
Options- A. 5 km/hr
- B. 23 km/hr
- C. 11.5 km/hr
- D. None of these of these Discuss
Correct Answer: 11.5 km/hr
Explanation:
Man's rate in still water = (14 + 9)/2 km/hr = 11.5 km/hr
- 4. A man can row with the stream at 11 km/hr and against the stream at 8 km/hr. The speed of the stream is?
Options- A. 3 km/hr
- B. 9.5 km/hr
- C. 1.5 km/hr
- D. 6 km/hr Discuss
Correct Answer: 1.5 km/hr
Explanation:
Speed of stream = (11 - 8)/2 km/hr = 1.5 km/hr
- 5. The speed of a boat in still water is 2 km/hr. If its speed upstream be 1 km/hr, then speed of the stream is?
Options- A. 2 km/hr
- B. 3 km/hr
- C. 1 km/hr
- D. None of these Discuss
Correct Answer: 1 km/hr
Explanation:
Speed in upstream = Speed in still water - Speed of stream.
? 1 = 2 - x
? x = 2 - 1 = 1 km/hr
- 6. A boat goes 14 km upstream in 56 minutes. The speed of stream is 2 km/hr. The speed of boat in still water is?
Options- A. 6 km/hr
- B. 15 km/hr
- C. 14 km/hr
- D. 17 km/hr Discuss
Correct Answer: 17 km/hr
Explanation:
? Speed upstream = 14 x (60/56) = 15 km/hr
Speed in upstream = Speed in still water - Speed of stream.
? x - 2 = 15
? x = 17 km/hr
- 7. The speed of a boat in still water is 10 km/hr. If its speed down stream be 13 km/hr, then speed of the stream is?
Options- A. 1.5 km/hr
- B. 3 km/hr
- C. 11.5 km/hr
- D. 5.75 km/hr Discuss
Correct Answer: 3 km/hr
Explanation:
Speed in still water + Speed of stream = Speed in downstream.
? 10 + y = 13
? y = 13 - 10 = 3 km/hr
- 8. The speed of a boat in still water is 12 km per hour. Going downstream it moves at the rate of 19 km per hour. The speed of the boat against the stream is?
Options- A. 5 km/hr
- B. 3 km/hr
- C. 8 km/hr
- D. Data inadequate Discuss
Correct Answer: 5 km/hr
Explanation:
Speed of stream = speed in downstream - Speed in still water
? Speed of stream = 19 - 12 = 7 km/hr
Speed of boat against stream = Speed in still water - Speed of stream.
? Speed of boat against stream = 12 - 7 = 5 km/hr
- 9. If a man rows at the rate of 5 km/hr in still water and his rate against the current is 3.5 km/hr, then the man's rate along the current is?
Options- A. 8.5 km/hr
- B. 6.5 km/hr
- C. 6 km/hr
- D. 4.25 km/hr Discuss
Correct Answer: 6.5 km/hr
Explanation:
Speed of current = 5 - 3.5 = 1.5 km/hr
Man's speed along the current = Man speed in still water + speed of current.
? Man's speed along the current = 5 + 1.5 = 6.5 km/hr
- 10. A man rows upstream 16 km and downstream 27 km talking 5 hours each time. What is the velocity of current?
Options- A. 2 km/hr
- B. 2.1 km/hr
- C. 1.1 km/hr
- D. None of these Discuss
Correct Answer: 1.1 km/hr
Explanation:
Man's rate upstream = 16/5 km/hr
Man's rate downstream = 27/5 km/hr
? Velocity of the current = (27/5 - 16/5)/2 km/hr = 1.1 km/hr
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