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 5 of 5.
Jain said:
1 decade ago
Let overall speed be 'v'.
And speed of stream be 'x'.
v = (48+48)/14 = 7.
And 4/(v+x)=3/(v-x) given.
Put the value of 'v' in above eq. and find 'x'.
And speed of stream be 'x'.
v = (48+48)/14 = 7.
And 4/(v+x)=3/(v-x) given.
Put the value of 'v' in above eq. and find 'x'.
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.
Anik said:
1 decade ago
@Rohit
It is impossible without assuming x i.e algebraic method, learn more on this.
It is impossible without assuming x i.e algebraic method, learn more on this.
Rohit said:
1 decade ago
Is there any other solotion without assuming the x ?
Manish said:
1 decade ago
We know that x=1/2, put this value in speed downstream= (4/x) then we get speed down stream=8km/h similarly we get speed upstream.
Manish said:
1 decade ago
Speed of down stream is always greater than upstream because in down stream the gravitational force enhence some speed of the stream.
Ram said:
1 decade ago
I'm also having this doubt. Anybody help me.
Rajesh said:
1 decade ago
So, Speed downstream = 8 km/hr, Speed upstream = 6 km/hr.
How we know these values 8 km/hr, 6 km/hr..
Pls tell me.
How we know these values 8 km/hr, 6 km/hr..
Pls tell me.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers