Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 7)
7.
The speed of a boat in still water in 15 km/hr and the rate of current is 3 km/hr. The distance travelled downstream in 12 minutes is:
Answer: Option
Explanation:
Speed downstream = (15 + 3) kmph = 18 kmph.
| Distance travelled = |  |
18 x | 12 |  km = 3.6 km. |
| 60 |
Video Explanation: https://youtu.be/IDOwWUeOldQ
Discussion:
21 comments Page 1 of 3.
Naresh said:
1 decade ago
Speed of the boat in still water (b) = 15 kmph.
Speed of the Current/Stream (s) = 3 kmph.
Speed of downstream (d) = b + s ==> 15 + 3 kmph ==> 18 kmph.
So,
It can travel 18 km in 1 hour.
So,
How many km it can travel in 12 min?
1 hour ====> 18 km.
12/60 hour ====>?
Do cross multiplications, then we get 18*1/5==>3.6.
Speed of the Current/Stream (s) = 3 kmph.
Speed of downstream (d) = b + s ==> 15 + 3 kmph ==> 18 kmph.
So,
It can travel 18 km in 1 hour.
So,
How many km it can travel in 12 min?
1 hour ====> 18 km.
12/60 hour ====>?
Do cross multiplications, then we get 18*1/5==>3.6.
(1)
Gautam said:
1 decade ago
Use the formula= if the speed of a boat in still water is U km/hr and the speed of the stream is V km/hr, then
speed down stream = (u+v)km/hr
(15+3)km/hr = 18 km/hr
Distance travelled = (18 x 12/60)=3.6km ANSWER
[60 is here because 1 minute=60seconds]
speed down stream = (u+v)km/hr
(15+3)km/hr = 18 km/hr
Distance travelled = (18 x 12/60)=3.6km ANSWER
[60 is here because 1 minute=60seconds]
Himanth said:
4 years ago
So simple, here they are given, speed of the boat in still water=15 and rate of current=3.
And time is given in 12 min, So we convert into hours 12/60 = 1/5.
He also given downstream flow,
Speed = Distance/time.
15 + 3 = D/1/5,
18 * 1/5 = D,
D = 3.6 km.
And time is given in 12 min, So we convert into hours 12/60 = 1/5.
He also given downstream flow,
Speed = Distance/time.
15 + 3 = D/1/5,
18 * 1/5 = D,
D = 3.6 km.
(3)
Sairam said:
9 years ago
@Lalitha.
Because time is in minutes, we have to change its unit of time from minutes to hours. So we have divide it.
If the distance is in meters then we have to multiply, to change it to seconds.
Because time is in minutes, we have to change its unit of time from minutes to hours. So we have divide it.
If the distance is in meters then we have to multiply, to change it to seconds.
Vinayak Mahadev said:
8 years ago
Speed of down stream= Still water speed + rate of current speed.
= 15 + 3 = 18.
18km/hrs for 1 hour (60 min).
Then find 12 min.
18 : 60
x : 12.
x= (12*18)/60 =3.6min.
That's all.
= 15 + 3 = 18.
18km/hrs for 1 hour (60 min).
Then find 12 min.
18 : 60
x : 12.
x= (12*18)/60 =3.6min.
That's all.
Nikul rana said:
10 years ago
Speed of still water = 15 kmph;
Speed of water current = 3 kmph;
Speed down stream = 18 kmph = 18 kmph;
Therefore; Distance traveled downstream = 18*12/60 = 3.6 km.
Speed of water current = 3 kmph;
Speed down stream = 18 kmph = 18 kmph;
Therefore; Distance traveled downstream = 18*12/60 = 3.6 km.
(1)
Satish said:
9 years ago
Speed of boat in still water and speed of boat are different.
Why all are using this same u + v for still water? It's not correct. Both are different.
Why all are using this same u + v for still water? It's not correct. Both are different.
Bindu said:
1 decade ago
Rate of current=1/2(downstream speed- upstream speed)
ie=1/2[(U+V)-(U-V)]
=1/2(U+V-U+V)
=2V/2
=V
SO RATE OF CURRENT = V(SPEED OF STREAM)
ie=1/2[(U+V)-(U-V)]
=1/2(U+V-U+V)
=2V/2
=V
SO RATE OF CURRENT = V(SPEED OF STREAM)
Likitha Ganta said:
2 years ago
Speed downstream = (15 + 3) kmph = 18 kmph. km.
Distance travelled = 18 * 12/60,
36/10 =>18/5 =>3.6km.
Distance travelled = 18 * 12/60,
36/10 =>18/5 =>3.6km.
(4)
Brajendra said:
2 decades ago
why we add current rate with speed of still water??it has to
substract
substract
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