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- Question
Amith can row a boat d km upstream and the same distance downstream in 5 hours 15 minutes. Also, he can row the boat 2d km upstream in 7 hours. How long will it take to row the same distance 2d km downstream for Amith ?
Options- A. 4 hrs 10 min
- B. 3 hrs 15 min
- C. 3 hrs 30 min
- D. 4 hrs 1 min
- Correct Answer
- 3 hrs 30 min
ExplanationLet the speed of boat and stream be x and y kmph respectively.
According to question
d/x+y + d/x-y = 5h 15m or 21/4 hrs ......(i)
and 2d/x-y = 7...... (ii)
From eq. (i) and (ii)
2d/x+y = 7/2
Hence, Amith will take to row 2d km distance downstream in 7/2 hrs
= 3.5 hrs
= 3 hrs 30 min.
- 1. A person can row 8 1/2 km an hour in still water and he finds that it takes him twice as long to row up as to row down the river. The speed of the stream ?
Options- A. 1.78 kmph
- B. 2.35 kmph
- C. 2.83 kmph
- D. 3.15 kmph Discuss
- 2. A man swims downstream 72 km and upstream 45 km taking 9 hours each time; what is the speed of the current ?
Options- A. 1 kmph
- B. 3.2 kmph
- C. 1.5 kmph
- D. 2 kmph Discuss
- 3. A man can row against the current three fourth of a kilometer in 15 min and returns same distance in 10 min, then ratio of his speed to that of current?
Options- A. 5:1
- B. 3:1
- C. 4:1
- D. 2:1 Discuss
- 4. Find the speed of stream if a boat covers 36 km in downstream in 6 hours which is 3 hours less in covering the same distance in upstream?
Options- A. 1.5 kmph
- B. 1 kmph
- C. 0.75 kmph
- D. 0.5 kmph Discuss
- 5. Rajesh rows in still water with a speed of 4.5 kmph to go to a certain place and comes back. Find his average speed for the whole journey, if the river is flowing with a speed of 1.5 kmph?
Options- A. 2 kmph
- B. 4 kmph
- C. 6 kmph
- D. 8 kmph Discuss
- 6. A motorboat 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 motorboat and speed of the water current respectively?
Options- A. 3:7
- B. 7:9
- C. 5:4
- D. 8:3 Discuss
- 7. 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
- 8. 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
- 9. 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
- 10. 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
Boats and Streams problems
Search Results
Correct Answer: 2.83 kmph
Explanation:
Given speed of the person = 8 1/2 = 17/2 kmph
Let the speed of the stream = x kmph
speed of upstream = 17/2 - x
speed of downstream = 17/2 + x
But given that,
2(17/2 - x) = 17/2 + x
=> 3x = 17/2
=> x = 2.83 kmph.
Correct Answer: 1.5 kmph
Explanation:
72 --- 9
? ---- 1
=> Down Stream = 8
45 ---- 9
? ---- 1
=> Up Stream = 5
Speed od current S = ?
S = (8 - 5)/2 = 1.5 kmph.
Correct Answer: 5:1
Explanation:
Let the speed of the man in still water = p kmph
Speed of the current = s kmph
Now, according to the questions
(p + s) x 10 = (p - s) x 15
2p + 2s = 3p - 3s
=> p : s = 5 : 1
Hence, ratio of his speed to that of current = 5:1.
Correct Answer: 1 kmph
Explanation:
Speed of the boat upstream = 36/9 = 4 kmph
Speed of the boat in downstream = 36/6 = 6 kmph
Speed of stream = 6-4/2 = 1 kmph
Correct Answer: 4 kmph
Explanation:
Let the distance in one direction = k kms
Speed in still water = 4.5 kmph
Speed of river = 1.5
Hence, speed in upstream = 4.5 - 1.5 = 3 kmph
Speed in downstream = 4.5 + 1.5 = 6 kmph
Time taken by Rajesh to row upwards = k/3 hrs
Time taken by Rajesh to row downwards = k/6 hrs
Now, required Average speed =
Therefore, the average speed of the whole journey = 4kmph.
Correct Answer: 8:3
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: 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: 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: 4 kmph
Explanation:
Speed of the current = 24-16/2
= 8/2
= 4 km/hr.
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