# 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:

38 comments Page 4 of 4.
Brinda Iyer said:
1 decade ago

But if in the same question distance traveled is asked, then what is the formula?

KottiTheKing 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

Then adding two equations u+v + u-v =11+5

2u=16

Finally, u=8.

Downstream speed is u-v = 5

Where u = speed of boat in still water and v is speed of stream

Then adding two equations u+v + u-v =11+5

2u=16

Finally, u=8.

Saloni nautiyal said:
1 decade ago

Formula for speed of boat in still water=[(X+Y)+(X-Y)]/2

where X=SPEED OF BOAT IN STILL WATER

Y=SPEED OF STREAM/CURRENT

THEREFORE, [(11+5)+(11-5)]/2=11

ANSWER=11

ANSWER IS NOT IN THE OPTIONS

where X=SPEED OF BOAT IN STILL WATER

Y=SPEED OF STREAM/CURRENT

THEREFORE, [(11+5)+(11-5)]/2=11

ANSWER=11

ANSWER IS NOT IN THE OPTIONS

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

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.

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?

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.

Ashok said:
1 decade ago

From where do this 1/2 came from?

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