Question

A man can row at 6 kmph in still water.
The river is running at the rate of 2 kmph
and it takes the man 270 minutes to tow
to a place and come back. How far is the
place?

● 10 km
● 12 km
● 8 km
● 16 km​

Answer 1

Given :

The speed of man in still water = x = 6 kmph

The speed of river = y = 2 kmph

The time taken by man for to and fro = 270 min = 4.5 hours

To Find :

The Total Distance that man travel

Solution :

∵ Time = $\dfrac{Distance}{Speed}$

For Down stream ,

Speed = x + y

           = 6 kmph + 2 kmph

          = 8 kmph

For Up stream

Speed = x - y

            = 6 kmph - 2 kmph

            = 4 kmph

∴  Total time = $\dfrac{D}{x+y}$ + $\dfrac{D}{x-y}$

Or,          4.5 =  $\dfrac{D}{8}$ + $\dfrac{D}{4}$

Or,          4.5 = $\dfrac{D+2D}{8}$

Or,     3 D = 4.5 × 8

Or,     3 D = 36

∴           D = $\dfrac{36}{3}$

i.e    Distance = 12 km

Hence, The distance cover by man is 12 km far the place   Answer

Answer 2

Answer:

the answer is : the place is 12 km far