Find the speed of the stream in Km/h.
Answer: (4) 3.0
Distance = 18km
Taken time by a person = 4 hours
Then, the speed of a person = 18/4 = 4.5km/h
Again, time taken by a person = 12h
Then, speed of a person = 18/12 = 1.5km/h
Speed of stream = (4 – 1.5)km/h
= 3.0 hm/h
Hence, the speed of stream is 3.0km/h.