Question

Q 9. A sailor goes 8km downstream in 40 minutes and returns in 1hr. Determine the speed of the
sailor in still water & the speed of the current.
Ek sailor bahav ki disha me 8km jane ke liye 40min aur wapas aane ke liye 1 ghanta leta hai. To
sailor ki speed shaant pani me aur bahav ka speed kya hoga.?
(a) Speed of sailor - 10km/hr, speed of current - 2km/hr
(b) Speed of sailor - 15km/hr, speed of current - 3km/hr
(c) Speed of sailor - 20km/hr, speed of current - 4km/hr
(d) Speed of sailor - 16km/hr, speed of current - 4km/hr​

Answer 1

Explanation:

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.

Answer 2

Hello good evening, have a great day✌✌