The speed of a boat in still water is 15 km/h, and the speed of the current is 5 km/h. In how much time (in hours) will the boat travel a distance of 60 km upstream and the same distance downstream?

9

We know that,

Upstream Speed = Speed of Boat – Speed of current

Downstream Speed = Speed of Boat + Speed of current

Let the speed of the boat = a and the speed of the stream = b

according to the concept

= \(\frac{60}{15 - 5}\) + \(\frac{60}{15 + 5}\) = Time

= Time = (\(\frac{60}{10}\) + \(\frac{60}{20}\))

=  (6 + 3) hr. = 9 hr