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- Question
A man can row 9 km/h in still water. It takes him twice as long as to row down. Find the rate of stream of the river?
Options- A. 3 1⁄3 Kmph
- B. 3 1⁄9Kmph
- C. 4 2⁄3 Kmph
- D. 4 1⁄3 Kmph
- Correct Answer
- 4 2⁄3 Kmph
Explanation
Let man’s rate upstream be x km/hr. Then his rate downstream is 3 x km/hr Given: Speed in still water = 9 (1/3) = 28/3 km/hr i.e, ½ (a+b) = 28/3 km/hr ½ (x+3x) = 28/3 2x = 28/3 x = 28/ 2 x 3 = 14/3 km/hr rate upstream b = 14/3 km/hr and rate downstream a = 14/3 x 3 = 14 km/hr speed of the current = ½ (a-b) = ½ (14 – 14/3) = ½ (42-14/3) = 28/6 = 4 (2/3) km/hr - 1. A boat sails 15 km of a river towards upstream in 5 hours. How long will it take to cover the same distance downstream, if the speed of current is one-fourth the speed of the boat in still water:
Options- A. 1.8h
- B. 3h
- C. 4h
- D. 5h Discuss
- 2. Two consecutive discounts x% and y% is equivalent to the discount
Options- A. (x-y+xy100)%
- B. (x+y+xy100)%
- C. (x-y-xy100)%
- D. (x+y-xy100)% Discuss
- 3. The certain worth of a certain sum due sometime hence is Rs. 1600 and the true discount is Rs. 160. The banker's gain is:
Options- A. 15
- B. 16
- C. 14
- D. 13 Discuss
- 4. The banker's discount of a certain sum of money is Rs. 72 and the true discount on the same sum for the same time is Rs. 60. The sum due is:
Options- A. 290
- B. 480
- C. 360
- D. 420 Discuss
- 5. What is the difference between the banker's discount and the true discount on Rs.8100 for 3 months at 5%
Options- A. Rs. 2
- B. Rs. 1.25
- C. Rs. 2.25
- D. Rs. 0.5 Discuss
- 6. A man went downstream for 28 km in a motor boat and immediately returned. It took the man twice as long to make the return trip. If the speed of the river flow were twice as high, the trip downstream and back would take 672 minutes. Find the speed of the boat in still water and the speed of the river flow.
Options- A. 12 km/hr, 3 km/hr
- B. 9 km/hr, 3 km/hr
- C. 8 km/hr, 2 km/hr
- D. 9 km/hr, 6 km/hr Discuss
- 7. A boat takes 19 hours for travelling downstream from point A to point B and coming back to a point C which is at midway between A and B. If the velocity of the stream is 4 kmph and the speed of the boat in still water is 14 kmph, what is the distance between A and B ?
Options- A. 180 km
- B. 160 km
- C. 140 km
- D. 120 km Discuss
- 8. A motor boat takes 12 hours to go downstream and it takes 24 hours to return the same distance. what is the time taken by boat in still water?
Options- A. 15 h
- B. 16 h
- C. 8 h
- D. 20 h Discuss
- 9. The current of a stream at 1 kmph. A motor boat goes 35 km upstream and back to the starting point in 12 hours. The speed of the motor boat in still water is ?
Options- A. 8 kmph
- B. 6 kmph
- C. 7.5 kmph
- D. 5.5 kmph Discuss
- 10. 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
Boats and Streams problems
Search Results
Correct Answer: 3h
Explanation:
Upstream speed = B-S
Downstream speed = B+s
B-S = 15/5 = 3 km/h
Again B= 4S
Therefore B-S = 3= 3S
=> S = 1 and B= 4 km/h
Therefore B+S = 5km/h
Therefore, Time during downstream = 15/5 = 3h
Correct Answer: (x+y-xy100)%
Correct Answer: 16
Explanation:
B.G. =(T.D.)^2/P.W.
= Rs. (160*160)/1600 = Rs. 16.
Correct Answer: 360
Explanation:
Sum =(B.D. x T.D.)/(B.D. - T.D.)
= Rs. (72 x 60) / (72 - 60)
= Rs. (72 x 60) /12
= Rs. 360.
Correct Answer: Rs. 1.25
Explanation:
F = Rs. 8100
R = 5%
T = 3 months = 1/4 years
Therefore BD - TD = 101.25-100 = Rs.1.25
Correct Answer: 9 km/hr, 3 km/hr
Explanation:
Let the speed of the boat = p kmph
Let the speed of the river flow = q kmph
From the given data,
=> 56p - 56q -28p - 28q = 0
=> 28p = 84q
=> p = 3q.
Now, given that if
Hence, the speed of the boat = p kmph = 9 kmph and the speed of the river flow = q kmph = 3 kmph.
Correct Answer: 180 km
Explanation:
Speed in downstream = (14 + 4) km/hr = 18 km/hr;
Speed in upstream = (14 ? 4) km/hr = 10 km/hr.
Let the distance between A and B be x km. Then,
x/18 + (x/2)/10 = 19 ? x/18 + x/20 = 19 ? x = 180 km.
Correct Answer: 16 h
Explanation:
If t1 and t2 are the upstream and down stream times. Then time taken in still water is given by
Correct Answer: 6 kmph
Explanation:
Speed of the stream = 1
Motor boat speed in still water be = x kmph
Down Stream = x + 1 kmph
Up Stream = x - 1 kmph
[35/(x + 1)] + [35/(x - 1)] = 12
x = 6 kmph
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
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