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- Question
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
- Correct Answer
- 4.5 km/h and 0.5 km/h
ExplanationDistance 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
- 1. 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
- 2. If the boat goes 7 kms upstream in 42 min and speed of the stream is 3 kmph, then the speed of the boat in still water ?
Options- A. 14 kmph
- B. 13 kmph
- C. 12 kmph
- D. 11 kmph Discuss
- 3. A boat while travelling upstream covers a distance of 29 km at the speed of 6 km/h, whereas while travelling downstream it covers the same distance at a speed of 12 km/h. What is the speed of the boat in still water?
Options- A. 6 kmph
- B. 8 kmph
- C. 9 kmph
- D. 11 kmph Discuss
- 4. A motorboat goes 8 km an hour in still water, but takes thrice as much time in going the same distance against the current than going with the current. Then find the speed of the current?
Options- A. 4 kmph
- B. 6 kmph
- C. 3 kmph
- D. 2 kmph Discuss
- 5. A motorboat takes half time to cover a certain distance downstream than upstream. What is the ratio between rate of current and rate of boat in still water?
Options- A. 1 : 3
- B. 3 : 2
- C. 2 : 3
- D. 3 : 1 Discuss
- 6. 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
- 7. 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
- 8. 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
- 9. 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 Discuss
- 10. 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
Boats and Streams problems
Search Results
Correct Answer: 9
Correct Answer: 13 kmph
Explanation:
Given that, upstream distance = 7 kms
Upstream speed = 7/42 x 60 = 10 kms
Speed of the stream = 3 kmph
Let speed in still water = M kmph, then
Upstream speed = M - 3 = 10
=> M = 13 kmph.
Correct Answer: 9 kmph
Explanation:
Speed of boat in still water = 1/2 (12 + 6) = 9 kmph.
Correct Answer: 4 kmph
Explanation:
Let the speed of current = 'C' km/hr
Given the speed of boat in still water = 6 kmph
Let 'd' kms be the distance it covers.
According to the given data,
Boat takes thrice as much time in going the same distance against the current than going with the current
i.e,
Hence, the speed of the current C = 4 kmph.
Correct Answer: 1 : 3
Explanation:
Let the speed of the boat in still water is 'w'
Speed of the current is 'c'
Let the distance between two places is 'd'
According to the question, motorboat takes half time to cover a certain distance downstream than upstream.
=> 2w - 2c = w + c
=> w = 3c
=> c : w = 1 : 3
Hence, the ratio between rate of current(c) and rate of boat in still water(w) = 1 : 3
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: 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: 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: 12 km
Explanation:
Speed 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
Correct Answer: 40
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