Question

a streamer goes downstream and covers difference btw two ports in 4 hrs while it covers the same distance upstream in 5 hrs. if speed of the stream is 2 km/hr. find the speed of streamer.

Answer 1

Ans: 18 km/hr

Solution 1

Let speed of the steamer in still water =x=x km/hr

Speed downstream =(x+2)=(x+2) km/hr
Distance between the ports =4(x+2)=4(x+2)km ---(1)

Speed upstream =(x−2)=(x−2) km/hr
Distance between the ports =5(x−2)=5(x−2)km ---(2)

From (1) and (2)
4(x+2)=5(x−2)4x+8=5x−10x=184(x+2)=5(x−2)4x+8=5x−10x=18
Solution 2

Let distance between the ports =d=dkm

Speed downstream =d4=d4 km/hr
Speed upstream =d5=d5 km/hr

Speed of the stream = 2 km
⇒d4−d52=2⇒d4−d5=4⇒d20=4⇒d=80⇒d4−d52=2⇒d4−d5=4⇒d20=4⇒d=80

Speed of the steamer in still water
=d4+d52=804+8052=20+162=18