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?
Answer & explanation
Correct answer: option 3
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