A man has to go from a port to an island and return. He can row a boat with a speed of 7 km/hr in still water. The speed of the stream is 2 km/hr. If he takes 56 minutes to complete the round trip, find the distance between the port and the island.

Question: A man has to go from a port to an island and return. He can row a boat with a speed of 7 km/hr in still water. The speed of the stream is 2 km/hr. If he takes 56 minutes to complete the round trip, find the distance between the port and the island.

Solution:
Speed upstream = 7 - 2 = 5 km/hr
Speed downstream = 7 + 2 = 9 km/hr

Let the distance between the port and the island be D km.
Also, we know that Time = Distance / Speed
⇒ (D/5) + (D/9) = 56/60
⇒ (14D)/45 = 56/60
⇒ D = 3 km

Therefore, the distance between the port and the island = 3 km