Question

A sailor goes 8Km downstream in 40 minutes and return in 1 hour determine the speed of sailor in still water and speed of current?

Answer 1

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Answer 2

Hi !

Let ,
Speed of sailor = x km/hr
Speed of current = y km/hr

total distance = 8 km

Speed of the sailor ,while going upstream = (x-y) km/hr

timeto go upstream = distance/speed
        = 8 /x- y  hrs

given ,

8/x - y = 1
x  - y = 8                  ----> [1]
==============================

total distance = 8 km
t = 40 min = 2/3 hrs

Speed of the sailor ,while going downstream = (x+y) km/hr

time to go upstream = distance/speed
        = 8 /x + y  hrs

given ,

8/x+y = 2/3

2(x+y) = 24
2x + 2y = 24

x + y = 12           ----> [2]
adding equations 1  and 2 ,


x + y = 12  
x  - y = 8 
-----------------
2x = 20

x = 10

x + y = 12

10 + y = 12

y = 2

Speed of sailor = x = 10 km/hr
speed of current = y = 2 km/hr