Aptitude - Boats and Streams - Discussion

s = d/t;
u-v = 2/1;

u-v = 2.
u+v = 2/10/60.
u+v = 12.

u = 7.
v = 5.

Final value = 5/7 which is less than a hour.

I can't understand, please help me.

How can rate upstream be 2 km/hr?

Divide 5 by 4 we get 0.25. So why the answer is 1 hr 15 min instead of 1 hr 25 min.

The question says a boatman goes 2 km against the current of the stream in 1 hour which means upstream so, it is 2km/hr.

Let Speed of the boat is 'u' and Speed of the Stream is 'v'.

Then u+v=6km/hr ///Speed of the boat in downstream.
Then u-v=2km/hr ////Speed of the boat in upstream.

Here we need the speed of the boat in Still Water which is 'u', because the speed of stream is zero in still water i.e;v=0.

By solving u+v =6 & u-v=2 ,we get u=4km/hr.

Ao, Speed of the boat in Stillwater is 4km/hr, then to travel 5km it take 1hr 15mins.

The ans must be 1hr 25mins.
5/4=1.25.
How it can be 1hr 15mins?

1hr = 60mins.

So, 1/4 of 1 hr = 1/4*60= 15min.

Thank you @Sonia.

Speed = Distance /Time.

Upstream Speed = 2/1 = 2 km/hr.
Downstream Speed = 1KM/10Min = 1/(10/60)hr = 1/(1/6) Km/Hr = 6 Km/Hr.

Now, Speed in Still Water = 1/2 (a+b)
a = Upstream speed means the speed of the boat against the current of the stream.
b. = Downstream speed means boat speed along the stream
= 1/2(2+6) after simplifying and is 4 Km/hr.

Total time required to travel distance of 5km for a boat in stationary water will be?

Time = Distance / Speed ----> Formula.

= 5/4 -> 4 km/hr is the speed of the boat in stationary water & 5 Km be the distance.
= 1.25 hr => 1 hr 15 min.
25/100 *60 = 15 for a minute to hour conversation.