Question

Difference between modern means of transmitting information over the old means of transmitting information

Answer 1

Answer:

$\huge\bf\underline\green{Answer}$

Given :-

Time taken for going downstream is 15 hours

Time taken for coming back to upstream is 20 hours

Speed of the water is 3km/hr

To Find :-

Speed of the down stream

Distance between the two Towns

Solution :-

➭ Let the speed of the stream be x km/hr

➭Therefore, Down stream speed will be

(x + 3) km/hr

➭ And, Upstream speed will be (x - 3) km/hr

Now, we know that

Distance = speed × time

➙ While going to downstream,

Distance = (x + 3) × 15

Distance = (15x + 45) km ------ (1)

➙ while going upstream,

Distance = (x - 3) × 20

Distance = (20x - 60)km -------(2)

Now, Distance covered by the streamer for going downstream and upstream are equal

By substituting values,

$\implies\sf{20x - 60 = 15x + 45}$

$\implies\sf{20x - 15x = 45 + 60}$

$\implies\sf{5x = 105}$

$\implies\sf{x = \dfrac{105}{5} }$

$\implies\sf\pink{x = 21}$

Hence, The speed of the streamer is 21 km/hr

Therefore, Downstream speed = (x + 3)

= (21 + 3) km/hr = 24 km/hr

So, Distance = Downstream speed × Time taken for going downstream

$\implies\sf{(24 \times 15)km}$

$\implies\sf\pink{360km}$

Hence, The Distance between two towns is 360km