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- Question
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
- Correct Answer
- 4 kmph
ExplanationLet 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.
- 1. A man can row upstream at 16 km/hr and downstream at 24 km/hr. Find the speed of the current.
Options- A. 4 kmph
- B. 6 kmph
- C. 5 kmph
- D. 3 kmph Discuss
- 2. 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
- 3. A boat can move 5 km/hr in still water. If the river is running at 1 km/hr, it takes it 75 min to move to a place and back. How far is the place?
Options- A. 3 kms
- B. 5 kms
- C. 6 kms
- D. 4 kms Discuss
- 4. A Woman?s downstream swimming rate is thrice of her upstream swimming rate. If she covers 12 km upstream in 2.5 hours, what distance she will cover in 5 hours downstream?
Options- A. 72 km
- B. 36 km
- C. 56 km
- D. 42 km Discuss
- 5. Sravan drove from home to a neighboring town at the speed of 50 km/h and on his returning journey, he drove at the speed of 45 km/h and also took an hour longer to reach home. What distance did he cover?
Options- A. 350 kms
- B. 450 kms
- C. 900 kms
- D. 700 kms Discuss
- 6. 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
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Boats and Streams problems
Search Results
Correct Answer: 4 kmph
Explanation:
Speed of the current = 24-16/2
= 8/2
= 4 km/hr.
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: 3 kms
Explanation:
Let the place be at a distance of 'd' kms
From the given data,
5d/12 = 5/4 => d = 3 kms.
Hence, the place is 3 kms far.
Correct Answer: 72 km
Explanation:
Rate of her upstream = 12/2.5 = 4.8 km/hr
Then, ATQ
Rate of downstream = 4.8 x 3 = 14.4 km/hr
Hence, the distance she covers downstream in 5 hrs = 14.4 x 5 = 72 kms.
Correct Answer: 900 kms
Explanation:
Let the distance he covered each way = d kms
According to the question,
d/45 - d/50 = 1
=> d = 450 kms.
Hence, the total distance he covered in his way = d + d = 2 d = 2 x 450 = 900 kms.
Correct Answer: 9 kmph
Explanation:
Speed of boat in still water = 1/2 (12 + 6) = 9 kmph.
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
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 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
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