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 1 of 4.
Vinayak shelke said:
3 months ago
8 is the answer.
Dhanmoni said:
3 years ago
In one hour, the boat goes the downstream = 11 km/h
On the other hand, the boat goes the upstream = 5 km/h,
So, the speed of the b.in still water is = d+u÷ 2.
= 11+5÷2
= 8 km/ h => answer.
On the other hand, the boat goes the upstream = 5 km/h,
So, the speed of the b.in still water is = d+u÷ 2.
= 11+5÷2
= 8 km/ h => answer.
(2)
Musoyiti said:
5 years ago
My way of solving is that;
Let the speed of the current be x.
So the speed in still water will be 11-x and 5 +x. Now as these both expressions are same so we use linear equation and find the value of x to be 3. So the speed of the current is 3 km/hr. So the speed of the boat in still water is 11-3=8.
Hence it is 8 km/hr.
Let the speed of the current be x.
So the speed in still water will be 11-x and 5 +x. Now as these both expressions are same so we use linear equation and find the value of x to be 3. So the speed of the current is 3 km/hr. So the speed of the boat in still water is 11-3=8.
Hence it is 8 km/hr.
(4)
A.K.BALAKRISHNAN said:
6 years ago
@All.
Follow this method for all boat question;
Downstream means boat towards the down in this situation we have to find the speed of boat and speed of stream.
Let x be boat speed.
Let y be stream speed.
1) Down stream speed = D/T(downstream time) = x+y
note: distance will be the same as both the streams.
2) Upper stream speed = D/T (upper stream time) = x-y.
Thank you.
Follow this method for all boat question;
Downstream means boat towards the down in this situation we have to find the speed of boat and speed of stream.
Let x be boat speed.
Let y be stream speed.
1) Down stream speed = D/T(downstream time) = x+y
note: distance will be the same as both the streams.
2) Upper stream speed = D/T (upper stream time) = x-y.
Thank you.
Vinau said:
7 years ago
X+Y=11,
X-Y=5,
X+Y+X-Y=11 + 5,
2X=16.
Then, X=8.
X-Y=5,
X+Y+X-Y=11 + 5,
2X=16.
Then, X=8.
(29)
Darkele said:
7 years ago
Note, there is no use of the 1 hour given because the upstream and downstream is sufficient to get the speed of the boat in still water.
(3)
Shandeepsamy said:
7 years ago
Where this 1/2 came from? Please explain.
(2)
HARI said:
7 years ago
For finding the speed of the boat in still water = (upstream-downstream/2).
For finding water speed = (upstream+downstream/2).
For finding water speed = (upstream+downstream/2).
(7)
Nurun Nobi Khokon said:
7 years ago
Let, downstream (with stream) speed= x.
upstream (against) speed is= y.
Now,
x = speed of the boat+speed of the water.
y = speed of the boat-speed of water.
-----------------------------------------------------------
x+y = 2*speed of the boat.
So, speed of the boat = (x+y)/2 [downstream speed+upstream speed].
upstream (against) speed is= y.
Now,
x = speed of the boat+speed of the water.
y = speed of the boat-speed of water.
-----------------------------------------------------------
x+y = 2*speed of the boat.
So, speed of the boat = (x+y)/2 [downstream speed+upstream speed].
(1)
Rz reddy said:
8 years ago
Downstream(D).
Upstream so(U).
D+U = 11.
D-U = 5.
2D = 16.
D = 16/2.
D = 8km/hr.
Upstream so(U).
D+U = 11.
D-U = 5.
2D = 16.
D = 16/2.
D = 8km/hr.
(1)
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