Question

A boat man takes an hour to go 8 km down stream and 1 hour and 40 minute to come back the same distance. Find the speed of the current.​

Answer 1

Answer:

Let the speed of the sailor in still water be x km/hr and speed of the current be y km/hr.

Then, speed of sailor downstream =x+y km/hr and speed of sailor upstream =x−y km/hr.

Distance covered =8 km.

Also, Time=

Speed

Distance

From the given information, we have,

x+y

8

=

60

40

and

x−y

8

=1

or,

x+y

8

=

60

40

=>

x+y

8

=

3

2

=>24=2(x+y)

=>x+y=12....(i)

Also,

x−y

8

=1

=>x=8+y....(ii)

Substituting (ii) in (i), we get,

x+y=12

=>8+y+y=12

=>2y=4

=>y=2

Substituting y=2 in equation (ii), we get,

x=8+y

=>x=8+2

=>x=10

Therefore, speed of sailor in still water =x=10 km/hr

and speed of the current =y=2 km/hr.