Question

A steamer goes downstream and covers the distance between two ports in 4 hours while it covers same distance upstream in 5 hours. if the speed of the stream be 2km/hr, find the speed of the steamer in still water​

Answer 1

Answer:

18km/hr

Step-by-step explanation:

Let the speed of the streamer in still water =x km/hr

the speed of the stream is 3 km/hr

Let the distance covered =d km

Speed downstream =x+3 km/hr

Time taken =5 hr

Distance=speed × time

d=5(x+3)

d=5x+15 ............ (1)

Speed upstream =x−3 km/hr

Time taken =7 hr

Distance=speed × time

d=7(x−3)

d=7x−21 ........... (2)

From (1) and (2),

7x−21=5x+15

7x−5x=15+21

2x=36

x=18 km/hr

Answer 2

Answer:

speed = 10km/hr

Step-by-step explanation:

let speed of steamer be x

speed up stream = speed of steamer - speed of stream

speed downstream = speed of steamer + speed of stream

$time_{upstream} = distance_{upstream} / speed_{upstream} \\time_{downstream} = distance_{downstream} / speed_{downstream}$

taking the ratios of times upstream and down stream since the distance is equal it will cancel out and the equation left will be

$speed_{downstream} = x + 2\\speed_{upstream} = x - 2$

$\frac{x-2}{x+2} = \frac{4}{5}$

5x - 2 = 4x + 8

x = 10km/hr