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 3 of 5.
Tamilazhagan said:
1 decade ago
Some body says why = 1/2. Solution is 48/(4/x)+48/(3/x) = 14.
Now 48x/4+48x/3 = 14.
Take x as common x(48/4+48/3) = 14.
Then x(12+16) = 14.
28x = 14.
x = 12.
Now 48x/4+48x/3 = 14.
Take x as common x(48/4+48/3) = 14.
Then x(12+16) = 14.
28x = 14.
x = 12.
Jagannath sahu said:
5 years ago
We have 48km in 14 hrs means 3km/he speed.
Now if we add and subtract stream of 1km/hr, then we will get 4km and 3km respectively.
So, the answer is 1km/hr.
Now if we add and subtract stream of 1km/hr, then we will get 4km and 3km respectively.
So, the answer is 1km/hr.
(1)
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'.
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.
Patchala.lokesh said:
6 years ago
Very simple it takes 3km/hr to travel down stream and 4km/hr to travel upstream so the difference b/w 4-3=1 is the rate of stream.
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.
Sunny said:
5 years ago
48/4 = 12.
48/3 = 16.
12+16 = 14.
Or, 1 = 1/2.
Sp down = 4/1/2 = 8kmph, sp up=3/1/2=6kmph.
Sp of stream = 1/2 (8-6) = 1kmph.
48/3 = 16.
12+16 = 14.
Or, 1 = 1/2.
Sp down = 4/1/2 = 8kmph, sp up=3/1/2=6kmph.
Sp of stream = 1/2 (8-6) = 1kmph.
(1)
Shanur Rahman said:
8 years ago
Suppose it took him x hrs to go downstream, then it will take him 14-x upstream. Therefore x/ (14-x) = 3/4.
There you go.
There you go.
Padma said:
1 decade ago
I am not able to understand why x=1/2 and,
Speed downstream = (4/x).
Speed upstream = (3/x).
Can anyone clear my doubt?
Speed downstream = (4/x).
Speed upstream = (3/x).
Can anyone clear my doubt?
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.
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