Question

A motor boat going downstream in a river covers the distance between points M and N in 4
hours, travelling upstream it covers the same distance in 5 hours. If the speed of the stream
is 3 km/h, find the speed of the steamer in still water.
M and N are two cities 450 km, apart. Two trains start at the same time​

Answer 1

Step-by-step explanation:

Let the distance covered be s,speed of boat in still water be x km/hr .

we k.n.t  distance = speed x time

Given time taken for downstream is 5 hrs.

net speed of boat in downstream is (x+1.5)      (∵ water helps in

Given time taken for downstream is 5.5 hrs.

net speed of boat in downstream is

s=(x−1.5)×5.5...............(ii)

Solving equations (i) and (ii)

s=(5x+7.5)=(5.5x−8.25)

⇒5x+7.5=5.5x−8.25

⇒5.5x−5x=7.5+8.25

⇒0.5x=15.75

∴x=0.515.75=31.5

∴ Speed of boat in still water is 31.5 km/hr

Answer 2

Answer:

31.5 km\h

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