Question

A boat man can row 36 km in downstream in 4 hours .if the speed of the current is 3km/h ,then find in what time will he be able to cover 6km upstream ?​

Answer 1

Step-by-step explanation:

1. It's Speed would be 36km/4h = 9km/h.

But due to accelerated 3km/h of downstream it's actual Speed would be =9km/h - 3km/h = 6km/h

Now due to upstream it's speed would decrease by 3km/h. Thus it's speed would be = (6-3)km/h = 3km/h.

Now, Time = distance/speed

There for time taken to cover 6km upstream is = (6/3) hours = 2 hours

Answer 2

Given :

• A boat man can row 36 km in downstream in 4 hours .
• Speed of current is 3km/h

To find : The time required to cover 6km in upstream.

Solution:

He can cover 6km in upstream in 2 hours

We can simply solve this mathematical problem by using the following mathematical process. (our goal is to calculate the time required to cover 6km in upstream)

Here, we will be using normal arithmetic method.

Downstream Speed = 36/4 = 9 km/h

And,

Downstream Speed = Speed of boat in still water + Speed of current

So,

9 = Speed of boat in still water + 3

Speed of boat in still water = 9-3 = 6 km/h

And,

Upstream Speed = Speed of boat in still water - Speed of current = 6-3 = 3 km/h

So,

In upstream he can cover 3km in = 1 hour

In upstream he can cover 1km in = 1/3 hour

In upstream he can cover 6km in = 6/3 = 2 hours

(This will be considered as the final result.)

Hence, in upstream he can cover 6km in 2 hours