Question

Rahamatchacha covers 30 miles in 6 hours in downstream and returns the same distance in 10 hours in upstream by his boat. Let us calculate and write the speed of Rahamatchacha's boat in still water and the speed of the stream too.​

Answer 1

Solution :-

Given : Rahamatchacha covers 30 miles in 6 hours in downstream.

And returns the same distance in 10 hours in upstream by his boat.

Let the speed of boat be x km/hr.

Speed of stream be y km/hr.

According to the question,

6(x + y) = 30

=> x + y = 5

=> x = 5 - y _______(i)

10(x - y) = 30

=> 10(5 - y - y) = 30 [from equation (i)]

=> 50 - 20y = 30

=> 20y = 20

=> y = 1

Putting value of y in equation (i),

=> x = 5 - 1 = 4

Hence,

Speed of boat in still water = 4 km/hr

Speed of stream = 1 km/hr

Answer 2

Solution :-

Let the speed of the boat be x km/h
and the speed of the stream be y km/h

A/q__

He covers 30 miles in 6 hours in downstream.

so, 6(x + y) =30

x + y = 30

so, x = 5 - y...........(I)

Now,

He returns the same distance in 10 hours in upstream.


so, 10(x - y) = 30

10( 5 - y - y) = 30 [because in equation (I) we got the value of x as 5 - y ]

50 - 20y = 30

So, 20 y = 20

Therefore y = 1

Now ,
x = 5 - y
=5-1
=4

Hence, the speed of boat in still water = 4km/h
and the speed of stream = 1km/h.

Thanks!!☜