Question

A boat takes 4 hours for travelling downstream from point A to point B aild coming back to point A upstream. If the velocity of the stream is 2 kmph and the speed of the boat in still water is 4 kmph, what is the distance between A and B?​

Answer 1

Answer:

Step-by-step explanation:

Speed of boat downstream =(4+2) km/hr =6 km/hr

Speed of boat upstream =(4−2) km/hr =2 km/hr

Let the distance between point A and point B be x km  

Then  

6

x

​

+  

2

x

​

−4

⇒  

6

x+3x

​

=4

⇒4x=24

⇒x=6 km

Answer 2

The distance between A and B point is 6 km.

Step-by-step explanation:

Given:

4 hours time is taken by boat  for travelling downstream from point A to B and coming back to point A upstream.

The stream velocity  is 2 kmph.

The  boat speed  in still water is 4 kmph.

To Find:

The distance between A point  and B point .

Formula Use:

Upstream  speed of boat  = (p−q) km/hr, where  p is the speed of the boat in still water and q is the speed of the stream           ---------formula no.01

Downstream speed of boat  = (p+q)Km/hr, where  p is the speed of the boat in still water and  q is the speed of the stream.       ----- formula no.02

Solution:

As given- The speed of the boat in still water is 4 kmph.

                  p=4 km/hr

As given - The stream velocity is 2 kmph.

                   q= 2 km/hr

Applying formula no. 01.

Upstream  speed of boat = p-q = 4-2 = 2 km/hr

Applying formula no. 02.

Downstream speed of boat= p+q= 4+2 = 6 km/hr

Let the distance between A and B point is z.

As given- 4 hours time is taken by boat  for travelling downstream from point A to B and coming back to point A upstream.

           $\frac{z}{6} + \frac{z}{2} = 4$      

             $\frac{z+3z}{6} = 4$

              4 z= 24

               z= 6 km        

Thus, the distance between A and B point is  6 km.