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- Question
Choose the most appropriate answer:A boat travels upstream from B to A and downstream from A to B in 3 hours. If the speed of the boat in still water is 9 Km/h and the speed of the current is 3 Km/h, the distance between A and B is
Options- A. 9 km
- B. 10 km
- C. 11 km
- D. 12 km
- Correct Answer
- 12 km
ExplanationSpeed of boat in still water = 9 km/hr
Speed of current = 3km/hr
Downstream speed = 9+3 = 12 km/hr
Upstream speed = 9-3 =6 km/hr
Let the distance between A to B be x km.
x/6 + x/12 = 3x + 2x = 36
3x = 36
x = 12 km - 1. A boat takes 2 hours to travel from point A to B in still water. To find out its speed upstream, which of the following information is/are required? A. Distance between point A and B. B. Time taken to travel downstream from B to A. C. Speed of the stream of water.
Options- A. Only A and B
- B. Only B and C
- C. All are required
- D. Any one pair of A and B, B and C or C and A is sufficient Discuss
- 2. Equal distance is covered by a boat in upstream and in downstream in total 5 hours. Sum of speed of a boat in upstream and downstream is 40 km/hr. Speed of boat in still water is 600% more than the speed of stream. Find theapproximate distance covered by boat in downstream (in km).
Options- A. 45
- B. 50
- C. 55
- D. 60 Discuss
- 3. Mahesh rows to the place 80 km away and back in 20 hours. He finds that he can row 8 km downstream in the same time as 4 km upstream. The speed of the boat in stillwater is
Options- A. 9 kmph
- B. 7 kmph
- C. 2 kmph
- D. 5 kmph Discuss
- 4. A boat travels 24 km upstream in 6 h and 20 km downstream in 4 h. then, the speed of a boat in still water and the speed of current are respectively
Options- A. 4.5 km/h and 3 km/h
- B. 4.5 km/h and 0.5 km/h
- C. 4 km/h and 2 km/h 5 km/h and 2 km/h
- D. 5 km/h and 2 km/h Discuss
- 5. A boat goes 4 km upstream and 4 km downstream in 1 hour. The same boat goes 5 km downstream and 3 km upstream in 55 minutes. What is the speed (in km/hr) of oat in still water?
Options- A. 6.5
- B. 7.75
- C. 9
- D. 10.5 Discuss
- 6. If a boat goes a certain distance at 30 km/hr and comes back the same distance at 60 km/hr. What is the average speed (in km/hr) for the total journey?
Options- A. 45
- B. 50
- C. 40
- D. 35 Discuss
- 7. A steamer moves with a speed of 4.5 km/h in still water to a certain upstream point and comes back to the starting point in a river which flows at 1.5 km/h. The average speed of steamer for the total journey is
Options- A. 12 km/h
- B. 10 km/h
- C. 6 km/h
- D. 4 km/h Discuss
- 8. A boat goes a certain distance at 40 km/hr and comes back the same distance at 24 km/hr. What is the average speed (in km/hr) for the total journey?
Options- A. 32
- B. 28
- C. 34
- D. 30 Discuss
- 9. Speeds of a boat along the current and against the current are 14 km/hr and 7 km/hr respectively. What is the speed of boat (in km/hr) in still water?
Options- A. 3.5
- B. 7.5
- C. 10.5
- D. 9.5 Discuss
- 10. The ratio of the speed of a boat downstream and speed of the stream is 9:1. If the speed of the current is 3 km per hr, find the distance travelled by the boat upstream in 5 hours.
Options- A. 100 km
- B. 98 km
- C. 109 km
- D. 105 km Discuss
Boats and Streams problems
Search Results
Correct Answer: Any one pair of A and B, B and C or C and A is sufficient
Explanation:
Let distance between A & B = d km
Let speed in still water = x kmph
Let speed of current = y kmph
from the given data,
d/x = 2
From A) we get d
From B) we get d/x+y
From C) we get y
So, Any one pair of A and B, B and C or C and A is sufficient to give the answer i.e, the speed of upstream.
Correct Answer: 50
Explanation:
let speed of boat= X, speed of stream= Y
Upstream speed= X-Y
Downstream speed= X+Y
Sum of upstream & downstream= (X-Y) +(X+Y)= 2X
So, 2X= 40
X= 20 km/hr
Speed of boat : speed of stream= 600+100 :100= 7:1
So speed of Stream= 20/7 km/hr
ATQ, D/( X-Y) + D/( X+Y) = 5
D/(120/7) + D/(160/7)= 5
D= 480×5/49= 48.97 km= 50 Km(approx)
Correct Answer: 9 kmph
Explanation:
Downstream speed = 8/X kmph
upstream speed = 4/X kmph
Now 80/(8/X) + 80/(4/X)=20
X=2/3
downstream Speed = 8/(2/3)= 12 kmph
upstream Speed = 4/(2/3)= 6 kmph
Rate of the stream = (12+6)/2= 9 kmph
Correct Answer: 4.5 km/h and 0.5 km/h
Explanation:
Distance travelled by boat in upstream=24km
Time taken = 6 h
Speed of the boat in upstream = 24/6 = 4 km/h
And distance travelled by boat in downstream = 20 km
Time taken = 4h Speed of the boat in downstream = 20/4 km/h = 5 km/h
Now, speed of the boat in still water = 1/2 [ speed of the boat in upstream + speed of the boat in downstream] =1/2 [4 + 5] = 1/2 × 9 = 4.5 km/h
And speed of the current = 1?2 [speed of the boat in downstream ? speed of the boat in upstream] = 1/2 [5 ? 4] = 1/2 × 1 = 0.5 km/h
Correct Answer: 9
Correct Answer: 40
Correct Answer: 4 km/h
Explanation:
Speed of streamer = 4.5 km/hrSpeed of water = 1.5 km/hr
Downstream speed = 4.5+1.5 = 6 km/hr
Upstream speed = 4.5 -1.5 = 3 km/hr
Average Speed = (6 X 3) / 4.5 = 4km/hr
Correct Answer: 30
Correct Answer: 10.5
Correct Answer: 105 km
Explanation:
Let the speed of boat in still water is ?x? km/hr & that of stream is ?y? km/hr.
Then, ATQ
(x+y)/y = 9/1 9y = x + y
x = 8y
y = 3 km/hr
So, x = 24 km/hr
Upstream speed = 24-3 = 21 km/hr
Hence, distance travelled upstream in 5 hours = 21*5 = 105 km.
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