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- Question
A boat running upstream takes 8 hours 48 minutes to cover a certain distance, while it takes 4 hours to cover the same distance running downstream. What is the ratio between the speed of the boat and speed of the water current respectively?
Options- A. 7:4
- B. 11:4
- C. 4:7
- D. 8:3
- Correct Answer
- 8:3
ExplanationLet the speed of the boat upstream be p kmph and that of downstream be q kmph
Time for upstream = 8 hrs 48 min = hrs
Time for downstream = 4 hrs
Distance in both the cases is same.
=> p x = q x 4
=> 44p/5 = 4q
=> q = 11p/5
Now, the required ratio of Speed of boat : Speed of water current
=
=> (11p/5 + p)/2 : (11p/5 - p)/2
=> 8 : 3
- 1. A man can row 6 kmph in still water. When the river is running at 1.2 kmph, it takes him 1 hour to row to a place and back. What is the total distance traveled by the man ?
Options- A. 4.58 kms
- B. 6.35 kms
- C. 5.76 kms
- D. 5.24 kms Discuss
- 2. A boatman can row 3 km against the stream in 20 minutes and return in 18 minutes. Find the rate of current ?
Options- A. 1/3 kmph
- B. 2/3 kmph
- C. 1/4 kmph
- D. 1/2 kmph Discuss
- 3. A man rows his boat 60 km downstream and 30 km upstream taking 3 hrs each time. Find the speed of the stream ?
Options- A. 5 kmph
- B. 10 kmph
- C. 15 kmph
- D. 45 kmph Discuss
- 4. A man goes down stream with a boat to some destination and returns upstream to his original place in 5 hours. If the speed of the boat in still water and the strean are 10km/hr and 14km/hr respectively, the distance of the destination from the string place is
Options- A. 16 km
- B. 18 km
- C. 21 km
- D. 25 km Discuss
- 5. A boy can swim in still water at 4.5 km/h, but takes twice as long to swim upstream than downstream. The speed of the stream is ?
Options- A. 1.8 kmph
- B. 2 kmph
- C. 2.2 kmph
- D. 1.5 kmph Discuss
- 6. A boat whose speed in still water is 9 kmph, goes 12 km downstream and comes back in 3 hrs. Find the speed of the stream?
Options- A. 1 kmph
- B. 3 kmph
- C. 5 kmph
- D. 4 kmph Discuss
- 7. A man can row 8 kmh in still water. If the river is running at 2 kmh, it takes 4 hrs more upstream than to go downstream for the same distance. Then the distance is given by
Options- A. 54 kms
- B. 32 kms
- C. 45 kms
- D. 60 kms Discuss
- 8. A motorboat can go 10 miles downstream on a river in 20 min. It takes 30 min for this boat to go back at the same 10 miles. Find the speed of the current ?
Options- A. 8 m/h
- B. 5 m/h
- C. 7 m/h
- D. 6 m/h Discuss
- 9. In one hour, a boat goes 12 km/hr along the stream and 6 km/hr against the stream. The speed of the boat in still water (in km/hr) is:
Options- A. 9
- B. 8
- C. 7
- D. 7.5 Discuss
- 10. If sum of upstream and downstream speed of a boat is 82 kmph, and the boat travels 105 km. upstream in 3 hr, Find the time taken by boat to cover 126 km downstream.
Options- A. 2.8 hrs
- B. 2.7 hrs
- C. 2.6 hrs
- D. 2.5 hrs Discuss
Boats and Streams problems
Search Results
Correct Answer: 5.76 kms
Explanation:
Speed in still water = 6 kmph
Stream speed = 1.2 kmph
Down stream = 7.2 kmph
Up Stream = 4.8 kmph
x/7.2 + x/4.8 = 1
x = 2.88
Total Distance = 2.88 x 2 = 5.76 kms
Correct Answer: 1/2 kmph
Explanation:
Speed in upstream = Distance / Time = 3 x 60/20 = 9 km/hr.
Speed in downstream = 3 x 60/18 = 10 km/hr
Rate of current = (10-9)/2 = 1/2 km/hr.
Correct Answer: 5 kmph
Explanation:
Speed of the boat downstream s=a/t= 60/3 = 20 kmph
Speed of the boat upstream s= d/t = 30/3= 10 kmph
Therefore, The speed of the stream = =5 kmph
Correct Answer: 21 km
Explanation:
Let the distance covered be D km.
10D = 42 x 5 = 210
=> D = 21 km
Correct Answer: 1.5 kmph
Explanation:
Speed of Boy is B = 4.5 kmph
Let the speed of the stream is S = x kmph
Then speed in Down Stream = 4.5 + x
speed in Up Stream = 4.5 - x
As the distance is same,
=> 4.5 + x = (4.5 - x)2
=> 4.5 + x = 9 -2x
3x = 4.5
x = 1.5 kmph
Correct Answer: 3 kmph
Explanation:
Let the speed of the stream = x kmph
From the given data,
=> x = 3 kmph
Therefore, the speed of the stream = 3 kmph
Correct Answer: 60 kms
Explanation:
Let the distance be d.
=> 2d = 120
=> d = 60 kms.
Correct Answer: 5 m/h
Explanation:
As the distance travelled is constant, the time taken is inversely proportional to speed.
Let 'u' be the speed of the current and 'v' be the speed of the boat.
Speed of the boat downstream = v + u & upstream = v - u
=> v+u/v-u = 30/20 => v/u = 5 => v = 5u
=> v + u = 6u = 10/20/60 miles/hr
=> 6u = 30 m/h
=> u = 5 m/h
Correct Answer: 9
Explanation:
Speed in still water = Average of Speed in Upstream and speed in Downstream
= 1/2 (12 + 6) kmph = 9 kmph.
Correct Answer: 2.7 hrs
Explanation:
Let Speed of boat in still water = b
Let Speed of still water = w
Then we know that,
Speed of Upstream = U = boat - water
Speed of Downstream = D = boat + water
Given, U + D = 82
b - w + b + w = 82
2b = 82
=> b = 41 kmph
From the given data,
41 - w = 105/3 = 35
w = 6 kmph
Now,
b + w = 126/t
=> 41 + 6 = 126/t
=> t = 126/47 = 2.68 hrs.
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