Question

. A motorboat whose speed is 18 km/h in still water takes 1 hour more to go 24 km upstream than to return downstream to the same spot, then the speed of the stream is *​

Answer 1

Answer:

speed=6km/h

Step-by-step explanation:

Given :

   The speed of the motor bike instill water is 18 kmph,

        

It takes 1 hour to travel upstream & return to same spot,.

From this information we can say that,

⇒ The speed of motor boat (boat's engine) = 18 kmph ,

⇒ It traveled 24 km upstream & 24km downstream in 1 hour,.

To Find :

The speed of stream .

We know that,

time = \frac{distance}{speed}

So,

Let the speed of stream be x,

Then,

we can say that,

...........seee attachment ....

Answer 2

Given:

• Speed of motorboat = 18 km/hr
• Distance to travel = 24 km
• Time taken more = 1 hour in upstream than in downstream.

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Need to Find :

• the speed of the stream in this question.

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We know,

Time = Distance / Speed.

Let:

• Speed of the stream be x

Then,

Speed of Upstream = 18 - x

Speed of Upstream = 18 - xDownstream speed = 18 + x

Now,

Time taken to travel upstream = Time taken to travel downstream + 1 hr

$\dfrac{24}{18 - x} = \dfrac{24}{18 + x} + 1$

$⟹\dfrac{24}{18 - x} = \dfrac{24 + 18 + x}{18 + x}$

$⟹ \dfrac{24}{18 - x} = \dfrac{42 + x}{18 + x}$

Cross multiplying,

$⟹24(18 + x) = (42 + x)(18 - x)$

$⟹432 + 24x = 756 - 24x - {x}^{2}$

$⟹{x}^{2} + 48x -324 = 0$

$⟹x(x + 54) - 6(x + 54) = 0$

$⟹(x + 54)(x - 6) = 0$

Then, x = -54 or 6

• But speed can't be negative. So, value for x is 6 km /hr.