Discussion
Home ‣ Aptitude ‣ Boats and Streams Comments
- 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 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
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: 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
Comments
There are no comments.More in Aptitude:
Programming
Copyright ©CuriousTab. All rights reserved.