# 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 1 of 4.
Vinau said:
6 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.

(22)

HARI said:
6 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).

(6)

Dhanmoni said:
2 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+uÃ· 2.

= 11+5Ã·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+uÃ· 2.

= 11+5Ã·2

= 8 km/ h => answer.

(2)

Musoyiti said:
4 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.

(2)

Darkele said:
6 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.

(2)

Shandeepsamy said:
6 years ago

Where this 1/2 came from? Please explain.

(2)

Yamini said:
7 years ago

If the speed downstream is a km/hr and speed upstream is b km/hr then,

Speed in still water=1/2(a+b)km/hr.

Speed in still water=1/2(a+b)km/hr.

(1)

Bhavesh said:
7 years ago

What is this same Q is like in 3 hours a boat goes 11 km along the stream and 5 km against the stream the speed of the boat in still water is?

(1)

Subaram said:
10 years ago

Here direction along the stream called downstream and against the stream called upstream. In this question they gave along the stream 11 kmhr against the stream 5 kmhr. So speed still in water = 1/2 (a+b) , here a downstream be up stream as for formula.

(1)

Rz reddy said:
7 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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