Question

A boat goes downstream and covers the distance between two ports in 5 hours while it covers the same distance upstream in
$5 \times \frac{1}{2}$
hours. Find the speed of boat in still water if the speed of stream is
$1 \times \frac{1}{2}$
km/hr​

Answer 1

Answer:

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Let the distance between the ports be D

Let us assume the speed of boat in still water to be Xkm / hr

Speed of steam is equal to 2 kilometre per hour

Speed of boat down the string will be :- X +2

We know Time = distance / velocity

So. 4 = D / X +2. (1)

Speed off the boat up stream will be :- X -2

So. 5 = D / X-2. (2)

Now dividing the equation 1 by equation 2

4/5. = D / X+2 ÷ D/X-2

4/5 = D / X+2 × (x-2) / D

4/5 = X-2 /X+2

4 (X+2) = 5 (X-2)

4X + 8 = 5X - 10

X= 18