Question

a man rows 27 km with the stream and 15 km against the stream taking 4 hours each time. Find this rate per hour in still water and the rate at which the stream flows.​

Answer 1

Answer:

wait a minute l will try it and say

Answer 2

Speed in still water is 5.25 km/hr and rate of stream is 1.5 km/hr

Solution:

Given that,

In water, the direction along the stream is called downstream

And, the direction against the stream is called upstream

Given that,

A man rows 27 km with the stream and 15 km against the stream taking 4 hours each time

Therefore,

Downstream distance = 27 km

Upstream distance = 15 km

Upstream time = 4 hours

Downstream time = 4 hours

Find downstream speed:

$speed = \frac{distance}{time}$

$Downstream\ speed = \frac{27}{4} = 6.75$

Similarly,

$Upstream\ speed = \frac{15}{4} = 3.75$

Find this rate per hour in still water and the rate at which the stream flows

$Speed\ in\ still\ water =\frac{1}{2}(a + b)$

Where, speed downstream is a km/hr and the speed upstream is b km/hr

Here, a = 6.75 km/hr and b = 3.75 km/hr

Therefore,

$Speed\ in\ still\ water =\frac{1}{2}(6.75 + 3.75)\\\\Speed\ in\ still\ water =\frac{10.5}{2}\\\\Speed\ in\ still\ water =5.25$

$Rate\ of\ stream = \frac{1}{2}(a-b)\\\\Rate\ of\ stream = \frac{1}{2}(6.75-3.75)\\\\Rate\ of\ stream = \frac{3}{2}\\\\Rate\ of\ stream = 1.5$

Thus, speed in still water is 5.25 km/hr and rate of stream is 1.5 km/hr

Learn more about this topic

If sum of upstream and downstream speed of a boat is 82 kmph, and the boat travels 105 km. upstream in 3 hr, Find the time taken by boat to cover 126 km downstream.

https://brainly.in/question/6988406

A man can row downstream 3km per hr faster than he can row upstream. In one hour he row 1km upstream and downstream back to the starting point. Find the speed while going down stream .

https://brainly.in/question/7744069