Question

a steamer is going downstream in a river cover distance between two ports in 12 hrs . coming back upstream , it covers this distance in 18 hrs . the speed of water is 4 km/hr . find the speed of boat ​

Answer 1

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Answer:

Given :-

a steamer is going downstream in a river cover distance between two ports in 12 hrs . coming back upstream , it covers this distance in 18 hrs . the speed of water is 4 km/hr

To Find :-

Speed of boat

Solution :-

Let the speed of boat be x km/hr

Now

When come upstream

x - 4 km/hr

When come downstream

x + 4 km/hr

Time to go downstream = 12 hr

Time to come upstream = 18 hr

Now,

S = D/T

S is the Speed

D is the Distance

T is the Time

Downstream = s/12 = (x + 4)

Upstream = s/18 = (x - 4)

s/18 × 12/s = (x + 4)/(x - 4)

18/12 = (x + 4)/(x - 4)

9/6 = (x + 4)/(x - 4)

6(x + 4) = 9(x - 4)

6x + 24 = 9x - 36

9x - 6x = 36 + 24

3x = 60

x = 20

Speed = 20 km/h

Answer 2

Answer:

Let the speed of the steamer in still water be x km/h.

Then, the speed downstream =(x+2) km/h

and the speed upstream =(x−2) km/h

Given, distance covered in 4 hours downstream = distance covered in 5 hours upstream

∴4(x+2)=5(x−2)

⇒4x+8=5x−10

⟹4x−5x=−10−8

[Transposing 5x to LHS and 8 to RHS]

⟹−x=−18 or x=18km/h

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