Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 15)
15.
A man rows to a place 48 km distant and come back in 14 hours. He finds that he can row 4 km with the stream in the same time as 3 km against the stream. The rate of the stream is:
Answer: Option
Explanation:
Suppose he move 4 km downstream in x hours. Then,
| Speed downstream = |  |
4 |  |
km/hr. |
| x |
| Speed upstream = | |
3 | |
km/hr. |
| x |
 |
48 | + | 48 | = 14 or x = | 1 | . |
| (4/x) | (3/x) | 2 |
So, Speed downstream = 8 km/hr, Speed upstream = 6 km/hr.
| Rate of the stream = | 1 | (8 - 6) km/hr = 1 km/hr. |
| 2 |
Discussion:
48 comments Page 2 of 5.
Surya said:
7 years ago
the speed of an up stream=x+y/2;
the speed of a down stream=x-y/2;
So they have given like 4km with the stream and 3km against the stream so
x+y/2=4;
x+y=8------------(1);
x-y=6-------------(2);
---------
2y=2;
-----------
y=1 rate of stream;
the speed of a down stream=x-y/2;
So they have given like 4km with the stream and 3km against the stream so
x+y/2=4;
x+y=8------------(1);
x-y=6-------------(2);
---------
2y=2;
-----------
y=1 rate of stream;
Raihan said:
4 years ago
Let speed in still water be x.
Let the speed of the stream be y.
So, 48/ (x+y) +48/ (x-y) =14 ---> equation(1)
And;
4/(x+y) =3/ (x-y)--> equation(2).
Solving the above two equations,
We get,
y = 1, Which is the answer.
Let the speed of the stream be y.
So, 48/ (x+y) +48/ (x-y) =14 ---> equation(1)
And;
4/(x+y) =3/ (x-y)--> equation(2).
Solving the above two equations,
We get,
y = 1, Which is the answer.
(5)
Adi said:
1 decade ago
My doubt is:
Is he rowing alternatively first 4 km downstream then 3 km upstream so he will cover 28 km @ 4km/hr and 20 @ 3km/hr (kind of work and time example 2 people working on alternate day with different capacity).
Is he rowing alternatively first 4 km downstream then 3 km upstream so he will cover 28 km @ 4km/hr and 20 @ 3km/hr (kind of work and time example 2 people working on alternate day with different capacity).
Faiz said:
1 decade ago
Let speed in still water be s.
Let speed of stream be x.
So, 48/ (s+x) +48/ (s-x) =14 - First equation.
and
4/ (s+x) =3/ (s-x) - Second equation.
Solving the above two equations,
We get,
X=1, Which is the answer.
Let speed of stream be x.
So, 48/ (s+x) +48/ (s-x) =14 - First equation.
and
4/ (s+x) =3/ (s-x) - Second equation.
Solving the above two equations,
We get,
X=1, Which is the answer.
Souvik masanta said:
5 years ago
He takes the same time for the 4 km with stream and 3 km against the stream
so,
Distance/speed = time.
4 /(x+y) = t ---> (1)
3/(x-y)= t ---> (2).
So, 4/(x+y)=3/(x-y).
x/y=7/1.
So, the rate of the stream =1km/h.
so,
Distance/speed = time.
4 /(x+y) = t ---> (1)
3/(x-y)= t ---> (2).
So, 4/(x+y)=3/(x-y).
x/y=7/1.
So, the rate of the stream =1km/h.
(3)
Rya said:
7 years ago
Total distance is 48 that means he travels 24km downstream and 24km upstream, why we are taking the whole 48km to calculate the separate down and upstream time? Please tell me.
Sean Simbota said:
1 decade ago
@Usamah.
If the speed downstream is Akm/hr and the speed upstream is Bkm/hr then;
Rate of stream = 1/2(A-B)km/hr.
Therefore;1/2(8-6).
= 1/2(2).
= 1 answer.
If the speed downstream is Akm/hr and the speed upstream is Bkm/hr then;
Rate of stream = 1/2(A-B)km/hr.
Therefore;1/2(8-6).
= 1/2(2).
= 1 answer.
Max said:
9 years ago
A man can row 24 km upstream and 54 km downstream in 6 hours. He can also row 36 km upstream and 48 km downstream in 8 hours. What is the speed of the man in still water?
Divya said:
8 years ago
Given : 4/x+y = 3/x-y --> (1).
by solving the eq > x =7y.
and : 48/x-y + 48/x+y = 14.
48//7y-y + 48/7y+y = 14.
48/6y + 48/8y = 14.
8 + 6 =14y,
14 =14y,
y = 1km/hr.
by solving the eq > x =7y.
and : 48/x-y + 48/x+y = 14.
48//7y-y + 48/7y+y = 14.
48/6y + 48/8y = 14.
8 + 6 =14y,
14 =14y,
y = 1km/hr.
Supriyo Mondal said:
3 years ago
Dw : Up.
Ratio of speed = 4 : 3,
Ratio of time = 3: 4,
= 6h : 8h ( Total time 14 hrs).
Then speed = 8kmph : 6 kmph,
Now speed of stream = 1/2 ( 8-6) = 1 kmph.
Ratio of speed = 4 : 3,
Ratio of time = 3: 4,
= 6h : 8h ( Total time 14 hrs).
Then speed = 8kmph : 6 kmph,
Now speed of stream = 1/2 ( 8-6) = 1 kmph.
(29)
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