Aptitude - Boats and Streams - Discussion
Discussion Forum : Boats and Streams - General Questions (Q.No. 5)
5.
In one hour, a boat goes 11 km/hr along the stream and 5 km/hr against the stream. The speed of the boat in still water (in km/hr) is:
Answer: Option
Explanation:
Discussion:
39 comments Page 2 of 4.
Debapriya dandapat said:
1 decade ago
Upstream relative speed is u + v=11km/hr
Downstream speed is u-v=5
Where u= speed of boat in still water and v is speed of stream
So adding two equations u+v + u-v =11+5
2u=16
So, u=8.
Downstream speed is u-v=5
Where u= speed of boat in still water and v is speed of stream
So adding two equations u+v + u-v =11+5
2u=16
So, u=8.
Ajit Jha(iit kharagpur) said:
1 decade ago
This Q is wrong buddy...
Here in stream dir. it takes 1 hour and again in downstream it takes 1 hour.
Then..
x+y=11/1=11------(1)
x-y=5/1=5----(2)
fm eq. 1 & 2.. we get..
x=8 km/h
Here in stream dir. it takes 1 hour and again in downstream it takes 1 hour.
Then..
x+y=11/1=11------(1)
x-y=5/1=5----(2)
fm eq. 1 & 2.. we get..
x=8 km/h
Arun.D said:
1 decade ago
Downstream=11km/hr.
Upstream=5km/hr.
Speed in still water = 1/2(a + b) km/hr.
a = upstream.
b = downstream.
Speed = 1/2(11+5)km/hr.
= 1/2(16)km/hr.
= 8km/hr.
Upstream=5km/hr.
Speed in still water = 1/2(a + b) km/hr.
a = upstream.
b = downstream.
Speed = 1/2(11+5)km/hr.
= 1/2(16)km/hr.
= 8km/hr.
Naresh said:
1 decade ago
Given that,
Speed in the downstream (d) = 11 km/hr.
Speed in the upstream (u) = 5 km/hr.
Speed of the Boat in still water = d + u/2.
=> 11 + 5/2 = 16/2.
=> 8 km/hr.
Speed in the downstream (d) = 11 km/hr.
Speed in the upstream (u) = 5 km/hr.
Speed of the Boat in still water = d + u/2.
=> 11 + 5/2 = 16/2.
=> 8 km/hr.
Ritha Epsiba said:
1 decade ago
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 downstream = (u + v) km/hr.
Speed upstream = (u - v) km/hr.
Speed downstream = (u + v) km/hr.
Speed upstream = (u - v) km/hr.
Vivek patidar said:
1 decade ago
Because in the condition of still position of water the speed one side and opposite side of water will be equal thats why we will take average of both speed.
Nija said:
10 years ago
In this question, it is not mentioned whether 1 hour each taken by downstream and upstream. So how can we solve this questions ? Please am confused.
Suchita said:
1 decade ago
Because in question they have mentioned speed of boat along the stream (i.e downstream) is 11km/hr and against the stream (i.e upstream) is 5km/hr.
Manjit singh said:
1 decade ago
Here speed along the stream and against the stream is given. Then how can we assume water to be steady (both the ways). Then why this 1/2 has come?
Aman kumar said:
9 years ago
B = Speed of boat.
w = Speed of water.
NOW
B + W=11 (with the stream)
B - W=5 (opp to stream)
----------------
2B =16,
B =16/2,
= 8 KMPH.
w = Speed of water.
NOW
B + W=11 (with the stream)
B - W=5 (opp to stream)
----------------
2B =16,
B =16/2,
= 8 KMPH.
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